Longeveron Mesenchymal Stem Cells (LMSCs) Delivered During Stage II Surgery for Hypoplastic Left Heart Syndrome (ELPIS)

This study is designed to assess the safety, tolerability, and efficacy of LMSCs as an
adjunct therapy to the standard stage II (BDCPA) surgical intervention for HLHS, which is
typically performed at 4 - 6 months after birth. LMSCs will be delivered via intramyocardial
injections.

A total of 30 patients will be enrolled in 2 stages with 3 Cohorts.

In the first stage, 10 consecutive HLHS patients will be enrolled and treated with LMSCs
(Cohort A). The first 3 patients will be treated no less than 5 days apart, and will be
evaluated for any treatment-emergent adverse events (TE-AEs) (e.g., induced myocardial
infarction or perforation). These patients will undergo full evaluation for 5 days to
demonstrate safety prior to proceeding with the remainder of the cohort. After 6 months
post-treatment of the last patient of Cohort A, a formal safety review will be conducted
prior to proceeding to the next phase.

The second stage is double-blinded, in which 20 HLHS patients will be randomized to either
receive treatment with LMSCs (Cohort B, 10 patients), or will receive no cells and no
injection (Cohort C, 10 patients).

Inclusion Criteria: all patients must have HLHS (all types) requiring BDCPA surgery.

Exclusion Criteria: all patients must not have any of the following.

1. Significant coronary artery sinusoids.

2. Requirement for mechanical circulatory support prior to BDCPA surgery.

3. Underlying evidence of arrhythmia requiring anti-arrhythmia therapy.

4. Need for concomitant surgery for aortic coarctation or tricuspid valve repair.

5. HLHS and restrictive or intact atrial septum.

6. Undergoing the Stage I (Norwood) procedure that does not have HLHS.

7. Serum positivity for: HIV; hepatitis B virus surface antigen (HBV BsAg); and/or
viremic hepatitis C virus (HCV).

8. Parent/guardian that is unwilling or unable to comply with necessary follow-up.

9. Unsuitability for the study based on the Investigator's clinical opinion.

10. Documented chromosomal abnormalities