BIOCOMPATIBILITY OF A SAFE BONE ALLOGRAFT (OSTEOPURE™) USED AS A SUPPORT FOR MESENCHYMATOUS STEM CELLS

Abstract

Purpose of the study: The mechanical and radiological course of bone allografts is often favorable but osteointegration properties could be improved. We associated a safe allograft with mesenchymatous bone marrow stem cells (MSC) with known osteogenic potential. The purpose of this preliminary study was to study the biocompatibility of the treated allograft, assess the osteoblastic differentiation properties of the MSC, and determine the optimal period for colonizing the bone matrix.

Material and methods: The support was a safe bone allograft preserved in a collagenic grid (Osteopure™). MSC harvested by adherence were seeded in a medium favoring osteoblastic differentiation by comparison with standard culture medium. Culture conditions varied to study the influence of the presence or not of support, the culture time, or the presence of human serum in the culture medium. For each culture medium, we noted: the number of cells, osteoblastic differentiation using markers: alkaline phosphate and osteocalcin. A histological study was also performed.

Results: Peak cell amplification was achieved at three weeks culture. Presence of osteoblastic differentiation markers was clearly identified in cultures grown in the presence of support material. Microscopy demonstrated that cells stimulated by the differentiation medium adhered strongly to the bone network. Histology revealed the presence of osteoblastic activity in differentiation medium with cells taking on the classical cytological aspect of osteoblasts. Cell proliferation was at least equivalent in medium with human serum as with fetal calf serum.

Discussion: This study demonstrated that the allogenic matrix does not modify the capacity of human MSC for colonization and differentiation. The cell organization is optimal compared with the absence of supporting material. Use of the patient’s own serum in the culture medium was validated enabling an autologous procedure. Use of a complex cell graft appears to be optimal after three weeks of culture. This first step proves the feasibility of the concept designed to optimize the support with the patient’s own MSC. The next step is to develop an in vivo model.