Nicolas Theys1, Gaëtan Thirion1, Sophie Vériter1, Valérie Lebrun1, Pierre-Yves Adnet1, Céline Caty1, Ali Modarressi2, Denis Dufrane1
1Novadip Biosciences, Mont Saint Guibert, Belgium
2Plastic, Reconstructive&Aesthetic Surgery department, University hospitals, Geneva, Switzerland
Introduction: Deep thickness skin wound remains a major challenge for reconstructive surgery. A novel approach of tissue engineering, based on an allogeneic adipose-derived 3D scaffold-free technology, is proposed.
Material and Methods: Adipose-derived stromal cells (ASCs) were isolated from human adipose tissue to constitute the 3D-graft. The manufacture involves a 3-step process: (1) collection of the starting material and isolation of ASCs; (2) Expansion of ASCs; (3) Differentiation and 3D induction by adding gelatin particles. The ultrastructure of the graft was assessed by microtomography/SEM. The protein and growth factors contents were determined by proteomic analysis (LC-MS/MS) and ELISA, respectively. The in vivo biocompatibility (inflammatory reaction, biodegradation) was assessed in nude and Wistar rats up to 4 weeks (n=20) as well as the safety in terms of tumorigenicity/toxicity/biodistribution. The efficacy was then evaluated in a xenogenic (human to rat) model of ischemic (vs. non-ischemic) wound in hyperglycemic Wistar rats (n=42, 3D grafts vs. sham/Ctrl+).
Results: The 3D-graft is a translucid and malleable membrane with a mean of 175±86 cells/mm² found to be embedded in the ECM with a low level of mineralization (0.30±0.31%v/v). The proteomic and genes analysis revealed the stimulation of the biological pathways involved in early wound healing and the over-expression of pro-angiogenic genes in the graft (in comparison to ASCs alone), respectively. The VEGF/SDF1a contents (181±12 and 663±27 ng/g, respectively) were also improved in the scaffold-free implant. The biocompatibility and the safety of the 3D-graft were confirmed at 4 and up to 24 weeks post-implantation, respectively. The 3D-graft was easily handled and applied (by a simple bandage) on the ischemic/hyperglycemic wounds (on the leg) and promoted an earlier wound closure (27 vs. 34 days for sham, respectively) associated with angiogenesis, dermis/epidermis reconstruction, transient and reversible increase of aSMA, lymphocytes/macrophages recruitment at 10-15 days.
Conclusion: Novadip developed a state-of-the art ATMP manufacturing platform for tissue engineering application. The scaffold-free approach with allogenic 3D-graft (derived from ASCs) demonstrated the safety and efficacy in stringent xenogenic model of hyperglycemic and ischemic deep-thickness wound. This graft improves wound healing in extreme conditions. The fully GMP compliant process is ready for scale-up and clinical applications.