Cranial reconstruction using allogeneic mesenchymal stromal cells: A phase 1 first-in-human trial

Cranial reconstruction is a critical procedure for patients who have undergone craniectomy due to trauma, stroke, or elevated intracranial pressure. While traditional methods rely on synthetic materials or autografts, recent advances in tissue engineering offer alternative approaches. Prior research has shown that mesenchymal stromal cells (MSCs) can support bone regeneration when combined with appropriate scaffolds. However, the use of allogeneic MSCs in cranial reconstruction remains unexplored. This gap motivated the development of a novel method using allogeneic MSCs seeded on a ceramic and polymer scaffold. No prior work had resolved how to ensure long-term stability of such constructs in the cranial environment. The need for a biocompatible, customizable solution led to the design of a three-dimensional printed construct. This study aimed to bridge the gap between tissue engineering and clinical application in cranial reconstruction. The challenge lies in translating laboratory findings into a safe and effective clinical procedure. The potential of MSCs in bone regeneration is well established, but their application in cranial voids requires further validation. This paper introduces a new approach to address the limitations of current reconstruction methods.

The goal of this study was to evaluate the feasibility of using allogeneic mesenchymal stromal cells (MSCs) in a customized scaffold for cranial reconstruction. The specific problem addressed is the lack of durable, biocompatible solutions for cranial defects following craniectomy. The motivation stems from the limitations of traditional materials, which may not integrate well with surrounding bone. This trial aimed to test a novel tissue engineering approach in a clinical setting. The method involved combining MSCs with a ceramic-polymer scaffold to promote bone regeneration. The study focused on safety, cosmesis, and bone formation outcomes. The use of allogeneic cells was chosen to avoid the need for autograft harvesting. The trial sought to demonstrate the potential of this approach in a first-in-human setting.

The study utilized a three-dimensional printed construct composed of two interlocking polymer meshes and ceramic granules. Patients underwent baseline computed tomography (CT) scans to design the construct. The inner mesh was placed during surgery, followed by cell-loaded ceramic granules and the outer mesh. MSCs were expanded in a good manufacturing practices facility and seeded onto the ceramic granules. The construct was implanted in the cranial defect. Follow-up assessments occurred at 3, 6, and 12 months. Cosmesis was evaluated visually, while bone formation was assessed by CT scans at 1 day, 3 months, and 12 months. The study design ensured customization of the construct for each patient. The use of rapid-prototyping allowed precise shaping of the scaffold. The combination of medical modeling and tissue engineering was central to the approach.

The construct was successfully manufactured and implanted in all three patients without complications. Initial cosmesis was excellent, with no adverse events reported. New bone formation was observed in CT scans at 3 months. However, bone resorption was noted in all three cases by the 12-month follow-up. The lack of rigidity in the construct may have contributed to incomplete bone formation. The ceramic-polymer scaffold provided structural support but did not fully integrate with surrounding bone. The study demonstrated the feasibility of using allogeneic MSCs in cranial reconstruction. The results suggest that while initial outcomes are promising, long-term stability remains a challenge. The combination of tissue engineering and rapid prototyping produced a viable construct. The findings highlight the need for further refinement of scaffold properties to enhance bone regeneration.

The authors concluded that a customized allogeneic MSC construct can be produced for cranial reconstruction with good initial cosmesis. The study demonstrated the potential of combining medical computer modeling, rapid prototyping, and tissue engineering in a clinical setting. The results suggest that while new bone formation occurred, long-term stability was limited. The lack of rigidity in the construct may prevent the formation of solid bone. The authors propose that further optimization of scaffold properties could improve outcomes. The use of allogeneic MSCs offers an alternative to traditional reconstruction methods. The findings support the feasibility of this approach in a first-in-human trial. The authors suggest that future studies should focus on enhancing scaffold stability to promote durable bone regeneration.