Acute Ischemic Stroke Clinical TrialPhase I Complete · Phase II Approved

Phase I Results

In a Phase I, open-label trial (NCT02433509) conducted at Hualien Tzu Chi Hospital in Taiwan, six patients (ages 45–80) with acute ischemic stroke received a single intravenous infusion of allogeneic human umbilical cord blood mononuclear cells (hUCB MNCs) within 9 days of stroke onset. Cord blood units were selected from StemCyte's public inventory based on ABO/Rh blood type compatibility and HLA matching (≥4/6).

The primary safety endpoint, incidence of graft-versus-host disease (GVHD) within 100 days, was met. No GVHD was observed in any patient. Mannitol was co-administered to facilitate blood-brain barrier penetration of the infused cells.

Landmark Case: Complete Motor Restoration

A 46-year-old male patient with hemiplegia (one-sided paralysis) due to acute ischemic stroke received a 6/6 HLA-matched cord blood infusion on day 8 after stroke onset. The unit contained 263 million mononuclear cells from a cord blood donation banked 17 years earlier.

Over 12 months, the patient demonstrated progressive neurological recovery across all measured outcomes. No serious adverse events or GVHD occurred during the study period. MRI imaging confirmed resolution of cerebral edema at 6 months post-infusion.

Full Phase I Cohort (6 Patients)

The complete Phase I results, published in the Tzu Chi Medical Journal in 2025, reported on all six enrolled patients (3 male, 3 female; mean age 65.8 years). A total of 40 adverse events occurred across the cohort, including 9 serious adverse events. Only transient erythema multiforme and hematuria were considered possibly related to the cord blood infusion. No GVHD was observed in any patient.

Safety Profile

The trial met its primary safety endpoint. No cases of graft-versus-host disease (GVHD) were observed within 100 days of transfusion across any patient. The two possibly treatment-related adverse events (skin reaction and blood in urine) were transient and resolved without intervention.

Rationale for Cord Blood in Stroke

Cryopreserved cord blood offers several advantages as a cell therapy for stroke. Cord blood is available off-the-shelf without donor recruitment delays, which is critical in the time-sensitive acute stroke window. Cord blood products carry a lower risk of graft-versus-host reaction compared to adult donor cells. Research has also shown that cryopreserved cord blood is significantly richer in anti-inflammatory cytokines (IL-10) and growth factors (EGF, VEGF, GM-CSF) that may support brain repair following ischemic injury.

Phase II: Approved & Advancing

Based on the Phase I safety and efficacy signals, both the U.S. FDA and Taiwan TFDA have authorized a Phase II, randomized, double-blind, placebo-controlled trial to assess the safety and efficacy of cord blood infusion in patients with acute ischemic stroke. This represents a significant advancement from the open-label Phase I design to a rigorous controlled study.

The Burden of Stroke

Acute ischemic stroke is the 2nd leading cause of death and 3rd leading cause of disability worldwide. More than 15 million people suffer a stroke annually. Approximately 30–35% die, and nearly 75% of survivors sustain permanent disability. Current acute-phase treatments (thrombolytics, anticoagulants) are strongly time-dependent and carry significant hemorrhage risk. There remains a critical unmet need for therapies that can promote neurological recovery beyond the initial intervention window.

Implications for Cord Blood Science

This study demonstrates that allogeneic cord blood MNCs may provide neuroprotective and neurorestorative benefits in acute ischemic stroke, a therapeutic application far beyond traditional hematopoietic reconstitution. The results support the hypothesis that cord blood-derived cytokines and growth factors can contribute to brain repair following ischemic injury, and that a single infusion from an unrelated donor can be administered safely without immunosuppression.

These findings, combined with StemCyte's Long COVID trial results, suggest that cord blood cell therapy may have applications beyond hematopoietic reconstitution. Further controlled studies are needed.

Sources: Lee et al. Cell Transplantation 2021; 30:1-7. Luo et al. Tzu Chi Medical Journal 2025. StemCyte press release, Jan 26, 2022. ClinicalTrials.gov NCT02433509.