R3 Stem Cell review finds intranasal regenerative biologics appear tolerable, but evidence is early

R3 Stem Cell researchers published the first systematic review of human studies on intranasal regenerative biologics for neurological disorders in Frontiers in Drug Delivery on Oct. 16, 2026. The review found no serious adverse events in 153 treated patients, but said the field still needs standardized dosing, better monitoring and controlled trials before clinical use can be considered.

Why it matters: - Intranasal delivery could offer a less invasive way to get regenerative biologics into the central nervous system. - The route may help bypass the blood-brain barrier, which limits most intravenous biologics from reaching the brain. - The review’s safety findings could shape how future neurological trials are designed. - The authors say the evidence is not strong enough to support clinical adoption yet.

What happened: - Researchers from R3 Stem Cell’s Department of Research and Development published a systematic review in Frontiers in Drug Delivery on Oct. 16, 2026. - The paper is titled “Intranasal delivery of regenerative biologics for neurological disorders: a systematic review of clinical studies.” - The review covers human clinical evidence for intranasal regenerative biologics across neurological conditions, biologic types and delivery methods. - The article appeared in the journal’s CNS Drug Delivery section. - The full open-access article is available here.

The details: - The review examined mesenchymal stromal cells, neural stem cells, exosomes, other extracellular vesicles, secretome, conditioned medium and breast milk-derived preparations delivered intranasally. - The team screened more than 18,600 records from PubMed, Google Scholar, ClinicalTrials.gov and the Chinese Clinical Trial Registry. - The search window ran from January 2015 through August 2026. - Researchers identified 16 publications describing 18 patient cohorts and 153 intranasally treated patients across 12 conditions. - The conditions included autism spectrum disorder, Alzheimer’s disease, Parkinson’s disease, ALS, Lewy body dementia, cerebral palsy, perinatal arterial ischemic stroke, hypoxic-ischemic encephalopathy and intraventricular hemorrhage in preterm infants. - Across follow-up periods of one to 39 months, investigators did not attribute a single serious adverse event to intranasal treatment. - The safety finding applied across all six biologic classes and all five delivery techniques identified in the review. - Reported side effects were generally mild and short-lived, including transient fever, headache, nasal irritation and discomfort at the application site. - Fifteen of the 18 cohorts reported clinical improvement, and one reported stabilization. - The authors say those findings should not be treated as proof of efficacy because the studies lacked control groups. - The review says placebo effects and the natural course of disease cannot be ruled out. - Most studies were small and uncontrolled. - Doses were reported in seven different ways, including cells, cells per kilogram, particles, micrograms of protein, milliliters, percentage concentrations and vial counts. - Five delivery techniques were used, ranging from nasal sprays to neuroendoscopic placement. - No study measured how much product was deposited in the nose or reached the brain. - Only Alzheimer’s disease, stem cells for Parkinson’s disease and intraventricular hemorrhage in preterm infants had replicated evidence from more than one cohort. - Twelve of the 18 cohorts were linked to a trial registration. - Only four registered trials used formal independent safety monitoring. - The review was prospectively registered with PROSPERO under CRD420261381627. - The authors followed PRISMA 2020 guidelines and SWiM recommendations. - Two independent reviewers extracted data and assessed risk of bias using Cochrane RoB 2, ROBINS-I and Joanna Briggs Institute checklists. - Because of heterogeneity across conditions, products and outcomes, the authors synthesized the results narratively rather than pooling them. - The authors are Umm E Habiba and Iqra Sarwar, Sabiha Shamim and David Lawrence Greene, MD, PhD, MBA. - All authors are employed by R3 Stem Cell LLC or R3 Medical Research LLC, as disclosed in the paper. - The work received no external funding. - R3 Stem Cell says its centers of excellence have performed more than 30,000 regenerative procedures to date, including intranasal stem cell therapy. - R3 Stem Cell says it operates more than 80 Centers of Excellence across eight countries.

Between the lines: - The review positions intranasal regenerative biologics as promising but highly fragmented. - The biggest problem is not just the size of the evidence base, but the lack of shared standards for dose, delivery and outcome measurement. - Without those standards, even positive signals are hard to compare across studies. - The absence of serious adverse events is encouraging, but the evidence still sits at an early-stage safety-and-feasibility level.

What’s next: - The authors call for standardized units for dose reporting. - They want consistent adverse-event classification. - They recommend shared outcome measures within each disease area. - They also call for clear characterization of delivery techniques and measurement of nasal deposition. - Where feasible, the authors want future studies to measure central nervous system bioavailability. - The paper says adequately powered, controlled trials are needed before clinical adoption can be considered. - David L. Greene said the goal is to give the field a baseline for tolerability and a roadmap for future trials. - Umm E Habiba said the review is intended as a practical framework for the next generation of studies.