CKD: From Preservation to Regeneration

Stem cells, organoids, and the future of kidney medicine

Nephrology · Seminar week 14 · released June 22, 2026 · includes a discussion video

Beyond dialysis and transplant: iPSC-derived nephrons, bioartificial kidneys, and CRISPR gene therapy. The science fiction that's becoming science fact.

Learning Objectives

1. Describe the mechanism of action of renal autologous cell therapy (REACT) and how it differs from conventional CKD management.
2. Evaluate the clinical trial evidence supporting Rilparencel in stages 3a-4 CKD, including eGFR stabilisation and safety outcomes.
3. Compare traditional preservation strategies (SGLT2 inhibitors, RAAS blockade, finerenone) with regenerative approaches across the CKD spectrum.
4. Discuss the potential implications of regenerative therapies on dialysis initiation, transplant waitlists, and long-term healthcare resource utilisation.
5. Assess patient suitability for cell-based therapies, including selection criteria, ethical considerations, and informed consent challenges in early-phase trials.

Section 1: The Scale of the Problem — CKD in 2026

Duration: 10 minutes

%%FIG0%% Teaching Point: Before we can discuss where CKD therapy is going, we need to understand why current approaches are insufficient. CKD affects approximately 850 million people worldwide, making it one of the most prevalent non-communicable diseases on the planet (PMID: 31506289). In the United States alone, the CDC estimates that 37 million adults — roughly 15% of the population — have CKD, though the majority remain undiagnosed (PMID: 35430015). The global burden has increased by approximately 29% over the last three decades, driven by the rising prevalence of diabetes, hypertension, and obesity (PMID: 32061315).

MUST ACT: The natural history of CKD is one of relentless progression. Despite optimal medical therapy, the average rate of eGFR decline in CKD stages 3-4 ranges from 2 to 5 mL/min/1.73m2 per year (PMID: 27383068). This means that a patient diagnosed with stage 3b CKD at age 55 with an eGFR of 35 mL/min may require dialysis initiation within 7-12 years. Once patients reach end-stage kidney disease (ESKD), outcomes are sobering: five-year survival on dialysis is approximately 35%, worse than many cancers (PMID: 30831896).

The economic burden is staggering. In the US, Medicare spends over $87 billion annually on CKD, with ESKD patients comprising less than 1% of the Medicare population but consuming approximately 7% of the total budget (PMID: 33711081). Globally, the cost of renal replacement therapy consumes 2-3% of healthcare budgets in high-income countries while remaining entirely inaccessible in many low- and middle-income settings (PMID: 31506289).

Say Out Loud: "When we say CKD is a global health crisis, this is not hyperbole. We are talking about a disease that affects one in ten adults, has a five-year dialysis survival rate worse than most solid-organ cancers, and consumes a disproportionate share of healthcare resources — yet our standard therapies can only slow the decline."

Nuance: It is worth noting that CKD progression is not uniform. The KDIGO 2024 guidelines emphasise risk stratification using the combination of eGFR and albuminuria (the "heat map") to identify patients at highest risk of progression (PMID: 36599783). Patients with an eGFR of 30-44 and A3 albuminuria (>300 mg/g) have a dramatically different trajectory compared to those with the same eGFR but A1 albuminuria. This stratification becomes critically important when we discuss which patients might benefit most from regenerative therapies.

Audience Poll: What proportion of CKD patients in your clinical experience are diagnosed before stage 3?

• A) Less than 20%
• B) 20-40%
• C) 40-60%
• D) Greater than 60%

Section 2: Current Standard of Care — What We Have and Where It Falls Short

Duration: 12 minutes

%%FIG1%% Teaching Point: The current pharmacological armamentarium for CKD has expanded significantly over the past decade, giving us reason for cautious optimism — but also underscoring the ceiling of what slowing progression can achieve.

RAAS Blockade remains the cornerstone of CKD management. ACE inhibitors and ARBs reduce proteinuria and slow GFR decline by approximately 2-3 mL/min/1.73m2 per year (PMID: 11794169). The RENAAL and IDNT trials established ARBs as standard of care in diabetic nephropathy over two decades ago (PMID: 11565518; PMID: 11565517). However, RAAS blockade does not halt progression — it merely reduces the slope of decline.

SGLT2 Inhibitors represent the most significant advance in CKD pharmacotherapy in the last decade. The DAPA-CKD trial demonstrated that dapagliflozin reduced the composite of sustained eGFR decline, ESKD, or death by 39% compared to placebo in patients with CKD stages 2-4, regardless of diabetes status (PMID: 32970396). The EMPA-KIDNEY trial extended these findings, showing empagliflozin reduced progression of kidney disease or cardiovascular death by 28% across a broad CKD population (PMID: 36331190). These are landmark results. But even with SGLT2 inhibition, CKD still progresses — just more slowly.

Finerenone, a non-steroidal mineralocorticoid receptor antagonist, has added another layer. The FIDELIO-DKD and FIGARO-DKD trials demonstrated that finerenone reduced the composite kidney outcome by 18% and cardiovascular events by 14% in patients with type 2 diabetes and CKD (PMID: 33264825; PMID: 34449181). The FIDELITY pooled analysis showed consistent benefits across the spectrum of diabetic CKD (PMID: 34921727).

GLP-1 Receptor Agonists are emerging as renoprotective agents. The FLOW trial demonstrated that semaglutide reduced the risk of major kidney disease events by 24% in patients with type 2 diabetes and CKD (PMID: 38785209). This adds yet another tool — but again, one that slows rather than reverses the disease.

Decision Point: Despite this expanding toolkit, the fundamental problem remains: all current therapies are preservative, not restorative. They reduce the rate of nephron loss but cannot regenerate nephrons that have already been destroyed. By the time a patient is diagnosed with CKD stage 3, they have already lost approximately 50% of their functional nephron mass. No currently approved therapy can restore that lost function. This is the gap that regenerative medicine aims to fill.

Say Out Loud: "We now have SGLT2 inhibitors, finerenone, GLP-1 agonists, and optimised RAAS blockade. These are genuine advances. But even with all four, we are still watching kidneys decline — just more slowly. The question is: can we move from slowing the fall to actually rebuilding?"

Audience Poll: In a patient with stage 3b diabetic CKD already on maximised RAAS blockade and SGLT2 inhibition, what is your primary concern?

• A) Residual cardiovascular risk
• B) Inevitable progression to dialysis despite therapy
• C) Hyperkalaemia from adding finerenone
• D) Patient adherence to a multi-drug regimen

Section 3: The Regenerative Paradigm — Renal Autologous Cell Therapy (REACT)

Duration: 15 minutes

%%FIG2%% MUST ACT: This section represents the conceptual centrepiece of the seminar. Renal autologous cell therapy (REACT), commercially developed as Rilparencel by ProKidney, is based on a fundamentally different premise than any existing CKD therapy: instead of slowing nephron loss, it attempts to restore renal function by reintroducing the patient's own selected renal cells into the diseased kidney.

Teaching Point: The mechanism involves three key steps:

1. Biopsy and Cell Selection: A percutaneous kidney biopsy is performed to obtain a small sample of renal cortical tissue. From this biopsy, specific populations of renal cells are isolated — primarily selected renal cells (SRC) that include tubular epithelial cells and other progenitor-like populations. These cells are expanded in culture under proprietary conditions designed to enrich for cells with regenerative potential (PMID: 27760051).

1. Cell Expansion and Characterisation: The isolated cells are expanded over 4-6 weeks to therapeutic quantities. Critical quality assessments include viability, identity markers (expression of tubular markers such as aquaporin-1 and Na/K-ATPase), and sterility. The density gradient separation selects for cells with higher oxygen consumption — a marker of metabolic activity and regenerative capacity (PMID: 27760051).

1. Percutaneous Injection: The expanded autologous cells are injected directly into the renal cortex under CT or ultrasound guidance. Multiple injection sites are used to distribute the cells throughout the cortex. The hypothesis is that these cells engraft, integrate into damaged nephron structures, and stimulate endogenous repair processes, including paracrine signalling that promotes anti-inflammatory and anti-fibrotic pathways (PMID: 33637973).

Nuance: The precise mechanisms by which injected SRC improve renal function remain an area of active investigation. Early preclinical work in rodent models of CKD demonstrated that SRC injection improved histological markers of tubular health and reduced interstitial fibrosis (PMID: 26620131). However, whether the benefit derives primarily from direct cellular engraftment and functional integration, or from paracrine effects (secretion of growth factors, anti-inflammatory cytokines, and extracellular vesicles that modify the local microenvironment), remains debated. Most current evidence suggests a paracrine-dominant mechanism, where the injected cells modulate the immune and fibrotic response rather than physically replacing lost nephrons one-for-one.

Say Out Loud: "Think of REACT not as a kidney transplant, but more like seeding a damaged garden. You're not replacing the whole garden — you're introducing cells that can signal to the remaining plants: stop dying, start growing. It's immunomodulation and regeneration, not replacement."

Decision Point: A critical question for clinical practice: if REACT works through paracrine mechanisms rather than direct nephron replacement, does this mean the therapy has a therapeutic window? In other words, is there a stage of CKD beyond which the remaining parenchyma is too fibrotic and too depleted of endogenous progenitors to respond to the paracrine signals? The Phase 2 data suggest that stages 3a-4 may be the sweet spot — enough remaining functional tissue to respond, but advanced enough that the benefit is clinically meaningful.

Case 1: The Early-Stage Dilemma

Presentation: A 52-year-old woman with type 2 diabetes and hypertension is found to have an eGFR of 52 mL/min/1.73m2 (stage 3a) and UACR of 450 mg/g on routine screening. She is already on lisinopril 20 mg, empagliflozin 10 mg, and metformin 1000 mg twice daily. Her eGFR has declined from 65 to 52 over the past 3 years (rate of decline approximately 4.3 mL/min/year). She asks: "Is there anything else that can be done before I end up on dialysis?"

Teaching Point: This patient exemplifies the clinical scenario where regenerative therapies could have the greatest impact. She is on optimised medical therapy but still progressing. At her current rate of decline, she will reach ESKD within approximately 8-10 years. Adding finerenone might slow this trajectory further (PMID: 33264825), but even with multi-drug therapy, the fundamental problem — loss of functional nephron mass — continues.

Decision Point: Should this patient be referred for a clinical trial of regenerative therapy? Consider:

• She is in the therapeutic window (eGFR 25-50 mL/min) that the REACT trials targeted
• Her residual renal mass may still be responsive to paracrine signalling
• However, she may also still have years of stable function on optimised medical therapy
• The risks of a renal biopsy for cell harvest (bleeding, infection, arteriovenous fistula) must be weighed against uncertain benefit
• Informed consent requires honest discussion that regenerative therapies remain investigational

Say Out Loud: "This is the patient who keeps you up at night. She's doing everything right, and she's still losing kidney function. The promise of REACT is that we might be able to change her trajectory — but the evidence is early, and the honest answer is: we don't yet know for certain."

Section 4: Clinical Trial Evidence — The REACT Programme

Duration: 15 minutes

%%FIG3%% MUST ACT: The REACT clinical trial programme has generated the most substantive clinical evidence for renal autologous cell therapy in CKD. Understanding these data — both their promise and their limitations — is essential for any clinician who will counsel patients about regenerative kidney therapies.

Teaching Point: Phase 1 (REGEN-001) The initial Phase 1 safety study enrolled 7 patients with CKD stages 3b-4 (eGFR 14-44 mL/min/1.73m2) who received a single injection of autologous SRC. The primary endpoint was safety, and no serious adverse events related to the cell injection were reported. Notably, the mean rate of eGFR decline appeared to slow or stabilise in treated patients compared to their pre-treatment trajectory, though this was not powered for efficacy (PMID: 27760051). The cell harvest procedure (percutaneous biopsy) was well tolerated with no significant bleeding complications.

Teaching Point: Phase 2 (REGEN-002/003) The Phase 2 programme expanded enrolment to a larger cohort of patients with CKD stages 3a-4 (eGFR 20-50 mL/min/1.73m2) of various aetiologies including diabetic nephropathy, hypertensive nephrosclerosis, and CKD of unknown cause. Patients received up to two injections of autologous SRC, 3-6 months apart. Key findings included:

• eGFR Stabilisation: Treated patients demonstrated a significant attenuation of eGFR decline compared to pre-treatment slopes. In some patients, eGFR stabilised or showed modest improvement over 12-24 months of follow-up (PMID: 33637973).
• Durability: The eGFR benefit appeared to persist for at least 24 months following injection, suggesting sustained biological activity rather than a transient effect.
• Safety: The overall adverse event profile was favourable. The most common procedure-related events were transient haematuria and mild biopsy-site pain. No cases of acute graft-versus-host disease (expected, given the autologous nature of the cells), tumour formation, or paradoxical acceleration of renal decline were observed.
• Biomarker Changes: Reductions in urinary MCP-1 (a marker of tubulointerstitial inflammation) and stabilisation of TNFR1 and TNFR2 levels (biomarkers associated with CKD progression) were observed in treated patients (PMID: 33637973).

Nuance: Several important limitations must be acknowledged:

1. Open-label design: The Phase 2 studies were open-label, meaning both patients and investigators knew who was receiving treatment. This introduces the possibility of bias in outcome assessment, particularly for endpoints like eGFR that can be influenced by hydration status, dietary protein intake, and concurrent medication changes.

1. Small sample size: The total number of treated patients in the Phase 2 programme was fewer than 100, limiting the statistical power to detect modest treatment effects and assess rare adverse events.

1. Historical controls: Comparisons to "expected" rates of eGFR decline based on pre-treatment slopes or published literature, rather than a concurrent placebo control, are inherently limited.

1. Selection bias: Patients enrolled in early-phase trials tend to be healthier, more motivated, and under closer surveillance than the general CKD population, which may inflate the apparent treatment effect.

Decision Point: How should clinicians interpret these data when counselling patients? The Phase 2 results are encouraging but not definitive. They support the biological plausibility of the approach and demonstrate an acceptable safety profile, but they do not yet constitute the level of evidence required to change clinical practice. The ongoing Phase 3 trial will need to demonstrate efficacy in a randomised, controlled, adequately powered design before REACT can be recommended outside of clinical trials.

Case 2: Interpreting Trial Data at the Bedside

Presentation: A 62-year-old man with biopsy-proven IgA nephropathy and CKD stage 3b (eGFR 38 mL/min/1.73m2) reads about the REACT trials online and asks his nephrologist if he can receive Rilparencel. He is currently on losartan 100 mg, dapagliflozin 10 mg, and has recently started finerenone 10 mg. His eGFR has declined from 50 to 38 over 4 years. UACR is 800 mg/g. He is frustrated: "I'm on three kidney drugs and still getting worse."

Teaching Point: This is a teaching moment about evidence-based medicine and the difference between promising early-phase data and proven therapy. Key counselling points:

1. REACT has shown encouraging results in Phase 1-2 trials, but has not yet been tested in a rigorous Phase 3 RCT.
2. His IgA nephropathy introduces a unique consideration: the REACT mechanism primarily targets tubular repair and fibrosis modulation, but IgA nephropathy is driven by glomerular immune complex deposition. Whether REACT can meaningfully influence a primarily glomerular disease process is unclear.
3. He could be referred for screening for the Phase 3 trial if inclusion criteria are met.
4. In the meantime, his current multi-drug regimen is evidence-based, and additional emerging options (e.g., anti-BAFF therapy for IgA nephropathy) may be relevant (PMID: 37326003).

Say Out Loud: "I understand the frustration of watching your kidney function decline despite doing everything right. The REACT data are genuinely exciting — but at this stage, they're a strong signal, not proof. What I can do is refer you for trial screening, so you can potentially access this therapy in the most rigorous and monitored setting."

Section 5: Comparing Paradigms — Preservation vs. Regeneration

Duration: 10 minutes

%%FIG4%% Teaching Point: To understand why regenerative approaches represent a true paradigm shift, it helps to contrast the philosophical underpinnings of the two approaches:

MUST ACT: The critical insight is that these approaches are not mutually exclusive. If REACT demonstrates efficacy in Phase 3 trials, the most likely clinical application would be as an adjunct to optimised medical therapy, not a replacement for it. A patient on SGLT2 inhibition and RAAS blockade who receives REACT would be simultaneously slowing nephron loss (preservation) and attempting to restore function in damaged nephrons (regeneration). This combinatorial approach could fundamentally change the trajectory of CKD.

Nuance: There is an important conceptual distinction between "regeneration" and "repair." True regeneration would imply the formation of new, structurally complete nephrons — a feat that has not been convincingly demonstrated in adult humans. What REACT more likely achieves is functional repair: improving the function of damaged but surviving nephrons through anti-fibrotic signalling, reducing inflammatory infiltrates, and potentially restoring tubular epithelial integrity. This distinction matters because it sets realistic expectations: REACT is unlikely to restore a patient from stage 4 CKD to normal kidney function, but it may prevent or substantially delay progression to ESKD.

Audience Poll: If REACT Phase 3 results are positive, when do you think regenerative cell therapy should be offered in the CKD trajectory?

• A) At diagnosis (stage 1-2) — prevent early damage
• B) Stage 3a-3b — the "sweet spot" with enough remaining function
• C) Stage 4-5 — last resort before dialysis
• D) Only after dialysis initiation — nothing to lose

Case 3: The Late-Stage Question

Presentation: A 71-year-old man with diabetic nephropathy, eGFR 18 mL/min/1.73m2 (stage 4-5), and UACR >3000 mg/g presents to the pre-dialysis clinic. He has a functioning AV fistula but has been hoping to avoid dialysis. He says he read about "kidney regeneration" therapy and asks if it could save him from dialysis. He is on insulin, amlodipine, losartan, dapagliflozin, and erythropoietin.

Teaching Point: This case forces us to confront the limits of regenerative therapy. At eGFR 18 with heavy proteinuria, this patient has severely depleted functional renal mass. Key considerations:

• The Phase 2 REACT trials enrolled patients with eGFR as low as 20 mL/min. Some showed stabilisation, but dramatic improvements from stage 5 back to stage 3 have not been demonstrated.
• The remaining parenchyma is heavily fibrotic. Whether there is sufficient viable tissue to respond to paracrine signalling is uncertain.
• A kidney biopsy for cell harvest carries elevated risk in advanced CKD (thinner cortex, higher bleeding risk, potential for inadequate cell yield).
• False hope is harmful: this patient needs to continue pre-dialysis planning (fistula care, transplant evaluation) while being honestly informed about the investigational nature of regenerative therapy.

Decision Point: The ethical obligation here is dual: neither to extinguish hope nor to provide false reassurance. The appropriate response is to acknowledge the research, explain its current limitations honestly, continue pre-dialysis preparation, and refer for trial screening if criteria allow — while making clear that dialysis planning should proceed in parallel.

Say Out Loud: "I want you to know about this research because it's real and it's promising. But I would not be doing my job if I told you to cancel your dialysis plans based on where the evidence is today. Let's pursue both tracks: we'll look into trial eligibility, and we'll make sure your fistula is ready."

Section 6: Patient Selection and Ethical Considerations

Duration: 10 minutes

%%FIG5%% Nuance: Patient selection for regenerative kidney therapy raises several unique ethical considerations that differ from standard pharmaceutical trials:

Biopsy Risk-Benefit Ratio: Unlike standard drug trials where the investigation involves taking a pill, REACT requires a percutaneous kidney biopsy for cell harvest. This introduces procedure-related risks (haemorrhage, infection, arteriovenous fistula, and rarely, nephrectomy) that must be weighed against an uncertain therapeutic benefit. The risk-benefit calculus changes depending on CKD stage: a biopsy in a patient with eGFR 45 carries different risk than one with eGFR 20 and a thin, scarred cortex.

Therapeutic Misconception: Patients with progressive CKD who face dialysis are vulnerable to the "therapeutic misconception" — the tendency to overestimate the personal benefit of participating in a clinical trial. The word "regeneration" itself may create unrealistic expectations. Informed consent processes must explicitly address the distinction between being treated and being studied (PMID: 16791394).

Equity and Access: Autologous cell therapy is resource-intensive. It requires a GMP cell manufacturing facility, specialised interventional radiology for injection, and 4-6 weeks of cell culture. If approved, the cost is likely to be substantial. This raises important equity questions: will regenerative therapies widen health disparities in CKD, or can they be made accessible across socioeconomic and geographic boundaries? The current cost of dialysis (~$90,000/year in the US) suggests that even expensive one-time therapies could be cost-effective if they delay or prevent ESKD.

Inclusion Criteria Considerations: The emerging selection criteria for REACT candidates include:

• eGFR 20-50 mL/min/1.73m2 (stages 3a-4)
• Stable or slowly progressive CKD (to ensure adequate cell yield from biopsy)
• Adequate cortical thickness on imaging (>1 cm) for safe biopsy
• Absence of active immunological disease (e.g., active lupus nephritis, ANCA vasculitis)
• No malignancy within 5 years
• Absence of severe interstitial fibrosis on biopsy (though this is only known after the initial biopsy)

Audience Poll: What do you consider the most challenging ethical issue in offering regenerative kidney therapy in clinical trials?

• A) Biopsy risk in patients with advanced CKD
• B) Therapeutic misconception and unrealistic expectations
• C) Cost and equity of access if approved
• D) Informed consent in patients facing dialysis (potential coercion by circumstance)

Case 4: The Informed Consent Challenge

Presentation: A 48-year-old man with FSGS (focal segmental glomerulosclerosis), eGFR 32 mL/min/1.73m2, has been screened and found eligible for a Phase 3 REACT trial. During the consent process, he says: "I'll do whatever it takes. I don't care about the risks — I just can't go on dialysis. My father was on dialysis for 8 years and it destroyed his quality of life."

Teaching Point: This patient's statement reveals several red flags for valid informed consent:

• His decision-making is driven by fear of dialysis rather than a balanced assessment of risks and benefits
• He explicitly dismisses procedural risks ("I don't care about the risks")
• His father's experience creates a powerful emotional driver that may impair rational decision-making

MUST ACT: Proper informed consent in this context requires:

1. Acknowledging his experience and fears explicitly — they are valid
2. Ensuring he understands this is a clinical trial, not established treatment, and he may receive placebo
3. Explaining that biopsy for cell harvest carries a small but real risk of complications
4. Clarifying that REACT has not been proven to prevent dialysis
5. Ensuring he has time to process this information and is not pressured by the trial enrolment timeline
6. Documenting his understanding, not merely his signature

Say Out Loud: "I hear you, and I understand why you feel this way. Your father's experience was real and difficult. But my job is to make sure you're choosing this with clear eyes. This trial might help you, or it might not. What I can guarantee is that we'll give you the best care regardless of what you decide about the trial."

Section 7: Future Directions — Beyond REACT

Duration: 10 minutes

%%FIG6%% MUST ACT: REACT/Rilparencel is the most clinically advanced regenerative kidney therapy, but it is not the only approach under investigation. The broader regenerative nephrology landscape includes several complementary and competing strategies:

Mesenchymal Stromal Cells (MSCs): MSC-based therapies, derived from bone marrow, adipose tissue, or umbilical cord, have been tested in CKD with mixed results. Unlike REACT (which uses kidney-derived cells), MSCs are not organ-specific but exert broad anti-inflammatory and immunomodulatory effects. A systematic review and meta-analysis found that MSC therapy improved eGFR and reduced proteinuria in small studies, but heterogeneity was high and long-term data limited (PMID: 31092229). The NEPHSTROM trial tested allogeneic bone marrow-derived MSCs in diabetic nephropathy and demonstrated safety but did not meet its primary efficacy endpoint (PMID: 37076170).

Kidney Organoids: Stem cell-derived kidney organoids represent a longer-term regenerative strategy. Researchers have generated nephron-like structures from human induced pluripotent stem cells (iPSCs) that contain podocytes, proximal tubular cells, and distal tubular segments (PMID: 26458176). However, these organoids currently lack a functional vasculature and collecting duct system, and their transplantation into animal models has produced only partially functional grafts. Clinical application is likely a decade or more away.

Exosome/Extracellular Vesicle Therapy: If the REACT mechanism is indeed paracrine-dominant, then the therapeutic cells themselves may not be necessary — their secreted extracellular vesicles (EVs) might be sufficient. EV-based therapies could potentially be manufactured at scale, stored off-the-shelf, and administered without a biopsy. Preclinical studies have shown that renal tubular cell-derived EVs can reduce fibrosis and improve function in rodent CKD models (PMID: 31649244). Clinical translation remains early.

Bioartificial Kidneys: The Kidney Project (University of California San Francisco) is developing an implantable bioartificial kidney that combines silicon nanotechnology membranes with bioreactors containing renal tubular cells. This device would provide continuous clearance without dialysis and without immunosuppression. Phase 1 human testing is anticipated within the next few years (PMID: 30949684).

Teaching Point: The regenerative nephrology field is evolving rapidly, and it is possible that the ultimate clinical application will involve a combination of approaches: autologous cell therapy to stabilise existing function, exosome therapy for maintenance, and eventually bioartificial devices or organoid transplantation for end-stage patients who have no remaining functional parenchyma.

Audience Poll: Which regenerative technology do you think is most likely to reach widespread clinical practice first?

• A) Autologous cell therapy (REACT/Rilparencel)
• B) Mesenchymal stromal cell therapy
• C) Kidney organoid transplantation
• D) Bioartificial kidney devices
• E) Exosome/extracellular vesicle therapy

Case 5: The Moonshot Patient

Presentation: A 35-year-old woman with Alport syndrome, eGFR 28 mL/min/1.73m2, asks about participating in a kidney organoid trial she read about in a news article. She has no family donors available and is on the deceased-donor transplant waitlist with an estimated wait time of 5-7 years. She is intellectually curious and understands the difference between bench research and clinical medicine.

Teaching Point: This case highlights the importance of differentiating between therapies at different stages of translational development:

• REACT/Rilparencel: In Phase 3 clinical trials. Potentially accessible via trial enrolment. Realistic near-term option for eligible patients.
• Kidney organoids: Preclinical. Not available in any human trial. At least 10-15 years from clinical application for CKD.
• For this patient: The most impactful immediate actions are optimising medical therapy (SGLT2 inhibitor, RAAS blockade), maintaining transplant listing, exploring living-donor campaigns, and screening for REACT trial eligibility if criteria overlap with her genetic diagnosis.

Decision Point: Alport syndrome is caused by mutations in type IV collagen genes, leading to progressive glomerulosclerosis. Since the genetic defect affects all of the patient's own renal cells, autologous cell therapy using her own defective cells may have limited efficacy — the transplanted cells carry the same genetic defect. This is a fundamental limitation of autologous approaches in genetic kidney diseases and illustrates why allogeneic or gene-corrected cell therapies may ultimately be necessary for these patients.

Section 8: Integration into Clinical Practice

Duration: 8 minutes

Teaching Point: As regenerative kidney therapies move toward clinical implementation, several practical considerations will shape how they are integrated into nephrology practice:

Referral Pathways: Nephrologists will need to identify patients in the optimal therapeutic window (stages 3a-4 with adequate cortical thickness and stable disease) and refer them to specialised centres with cell therapy capabilities. This mirrors the hub-and-spoke model used for solid-organ transplantation.

Monitoring Protocols: Post-injection monitoring will require serial eGFR measurements, urine biomarkers (MCP-1, KIM-1, NGAL), and imaging to assess for adverse events. Standardised monitoring protocols have not yet been established and will need to be developed based on Phase 3 outcomes.

Combination Therapy: The most likely clinical paradigm will involve continued medical therapy (SGLT2 inhibitor + RAAS blocker +/- finerenone +/- GLP-1 RA) with the addition of autologous cell therapy for eligible patients. This multi-modal approach — preservation plus regeneration — could yield additive or synergistic benefits.

Cost-Effectiveness Modelling: If REACT delays dialysis initiation by even 3-5 years, the cost savings would be substantial. At approximately $90,000/year for haemodialysis in the US, a 5-year delay would save $450,000 per patient. Even with manufacturing costs of $100,000-200,000 per treatment course, the therapy could be cost-effective from a healthcare system perspective (PMID: 33711081).

Say Out Loud: "The future of CKD management is not preservation OR regeneration — it's preservation AND regeneration. The question is not whether to use new therapies, but when and in whom. And that requires the same rigorous evidence-based approach we apply to everything else in medicine."

Tonight on Shift — Six Things to Remember

1. CKD is a one-way street with current therapies. SGLT2 inhibitors, RAAS blockade, finerenone, and GLP-1 agonists slow the decline — but none can restore lost nephron function. The five-year dialysis survival rate of 35% underscores the urgency for new approaches.

1. REACT uses the patient's own kidney cells. Autologous selected renal cells are harvested via biopsy, expanded in culture, and re-injected into the renal cortex. The mechanism is predominantly paracrine: anti-fibrotic and anti-inflammatory signalling to surviving nephrons.

1. Phase 2 data are encouraging but not definitive. eGFR stabilisation for up to 24 months has been demonstrated, with a favourable safety profile. But these were open-label, small studies. Phase 3 RCT results are needed before clinical adoption.

1. Patient selection matters. The therapeutic window appears to be eGFR 20-50 mL/min (stages 3a-4) with adequate cortical thickness. Too early may not show benefit; too late may lack viable tissue to respond.

1. Ethical landmines are real. Therapeutic misconception, biopsy risk in advanced CKD, and equity of access are challenges that must be actively addressed in consent processes and health policy.

1. The future is combinatorial. REACT, exosome therapy, kidney organoids, and bioartificial kidneys are complementary — not competing — technologies. The next decade will determine which approaches translate from bench to bedside.

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