Absence of muscle regeneration after implantation of a collagen matrix seeded with myoblasts

Abstract Collagens are widely used as biomaterials for e.g. soft tissue reconstruction. The present study was aimed at reconstruction of abdominal wall muscle using processed dermal sheep collagen (DSC) and myoblast seeding. Myoblasts were harvested from foetal quadriceps muscle of an inbred rat strain, cultured, seeded as non-differentiated cells into DSC-discs and incubated in vitro for 2 h. The discs were implanted in the abdominal wall defects in adult rats. Non-seeded discs functioned as control. Implantation periods till week 6 were chosen. At day 1 and 2 after implantation infiltration of granulocytes and macrophages was clearly more intense in the seeded discs than in the controls. Relatively large numbers of mast cells infiltrated from the side of the adhering omentum. In central areas of the discs, seeded cells were easily recognized till day 5, since non-seeded control discs did not contain such cells. Ingrowth of host cells and tissue at the margins proceeded faster with the seeded discs. Lymphocyte accumulations were observed in the 3 week seeded specimen. At week 3 and week 6, in the seeded discs muscle tissue was not present, in contrast to very large giant-like cells. It is concluded that the chosen method of myoblast seeding did not result in the regeneration of muscle during this observation period. Unfavorable circumstances such as humoral factors, direct cellular interactions (phagocytosis), indirect cellular interactions (cytokines), or initial absence of vascularization, may play a role. Further studies are required.