This study is testing if a special injection called Lomecel-B™ can help people with a heart problem known as Hypoplastic Left Heart Syndrome (HLHS). HLHS is a condition where the left side of the heart is underdeveloped. Lomecel-B™ uses mesenchymal stem cells (MSCs), which are special cells that can become other types of cells like heart or muscle cells. These MSCs come from the bone marrow of healthy donors and don't need to match your body exactly.

To join the study, you must have HLHS and need a specific heart surgery called Stage II palliation. Unfortunately, you can't join if you need extra support for your heart right before surgery, have other specific heart issues needing surgery, or certain infections like HIV or hepatitis. You also can't join if you have a pacemaker or are allergic to a substance called DMSO.

• The study is for those needing Stage II palliation for HLHS.
• Certain medical conditions may exclude you from participating.
• It's important to follow up with the study team after treatment.