519 Development and Use of an Intraoperatively Usable Hand-Held Bio-Printer Delivering Mesenchymal Stem Cells In-situ

Bio-Printing is a promising delivery strategy and is evolving in all disciplines in medicine including printing skin tissue and delivering cells for skin regeneration. Skin regeneration is essential for survival especially in severely burned patients. Mesenchymal stem cells (MSCs) are known for their wound healing and tissue regeneration potential, but the treatment routine and consistent delivery of these MSC represents a challenge. However, most extrusion based bioprinters are designed for in vitro use with dimensions that exceed the ones of the printed tissues, thereby limiting their clinical relevance in large area burns. We have designed and validated in vitro a novel flexible intraoperatively usable light-weight (850g) hand-held bio-printer that overcomes these limitations and shares the form factor of a dermatome. With this hand-held design it is possible to cover large surface areas with different shapes and ankles. Furthermore, this device delivers MSC directly and conformally on the wound, embeeded within an extracellular matrix layer. Our aim is to assess the functionality of this device with this intraoperatively usable system. We conducted in vitro experiments and additional a prospective in vivo experimental large animal study, applying umbilical cord mesenchymal stem cells (UC-MSC) with a hand-held bio-printer in situ in a large full-thickness burn wound healing model, evaluating cell viability after depositioning. The bio-printer deposit fast MSC in an precise pattern embeeded in a 0,12 mm thick stable ECM layer on the wounds. MSC survive >7 days (live/dead staining) with an overall viability of 90% in vitro. We were able to trace viable depositioned stem cell in vivo 2-3 days post-printing microscopically and with flowcytometry. This easy usable new hand-held bio-printer depositions intraoperatively successful MSC onto wounds and hence bears the great potential of being an alternative of covering large burned wounds for wound healing and skin regeneration. The data herein demonstrated that our bio-printer, engineered for the purpose of a intraoperatively cell delivery, has the ability of delivering a fairly high amount of viable cells which we were able to demonstrate in vitro, as well as in vivo considering the fact of a real scenario of cell harvesting in the morning in a laboratory, cell delivery in a syringe to the OR and real-time cell depositioning in-situ with a bio-printer on a living, moving wound healing model which needs regular bandage changes, which bears the high risk of cell-delivery failure. This supports a potential clinical trial as a next step.