External Liver Assist System Receives FDA RMAT Designation

Acute liver failure can develop over days to weeks and is often fatal when transplantation is not possible or unavailable. Although some patients recover spontaneously, many deteriorate rapidly amid a persistent shortage of donor organs. Hospitals need temporary liver support options that can stabilize candidates for recovery or transplant. A new external liver assist system has received U.S. Food and Drug Administration Regenerative Medicine Advanced Therapy (RMAT) designation, creating an expedited development pathway based on preliminary clinical evidence.

United Therapeutics’ investigational miroliverELAP, developed by its wholly owned subsidiary Miromatrix Medical Inc., is designed to provide temporary liver support for patients with acute liver failure (ALF). The system is described as an external liver assist product comprising an external blood circuit and a single‑use bioengineered liver sustained outside the human body. The company notes that miroliverELAP remains investigational and is not approved for any use in any country.

The bioengineered organ is manufactured by seeding a decellularized porcine liver scaffold with allogeneic human endothelial cells and human liver cells isolated from donated human livers. These donor livers are not suitable for transplantation and are supplied by organ procurement organizations. The approach is intended to deliver temporary hepatic support while leveraging otherwise unusable donor tissue.

The U.S. Food and Drug Administration granted the RMAT designation to miroliverELAP. RMAT is a specialized program to accelerate development and regulatory review of promising regenerative medicine therapies for serious conditions with unmet needs, contingent on preliminary clinical evidence of potential efficacy. Designation provides intensive FDA guidance on efficient study design and endpoints and confers regulatory advantages such as eligibility for priority review, rolling review of Biologics License Application materials, and enhanced organizational engagement to expedite development.

In January, the company announced positive results from a phase 1 study of miroliverELAP in patients with acute forms of liver failure, acute‑on‑chronic liver failure, and severe acute alcoholic hepatitis, collectively referred to as ALF; full results are expected in the second half of 2026. ALF affects thousands of patients annually and is marked by rapid loss of hepatic function over days or weeks. Approximately 45% of patients recover spontaneously, 25% undergo liver transplantation, and about 30% die because they are ineligible for transplant or cannot receive one in time.

“Receiving this designation from the FDA highlights both the critical unmet need we are addressing and the promising potential of miroliverELAP as a novel therapeutic option,” said Jeff Ross, Ph.D., President of Miromatrix. “We look forward to continuing our collaborative exchange with the FDA as we advance the clinical development of miroliver ELAP for patients with acute liver failure.”

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