gms | German Medical Science

Introduction: In many cases, complex injuries of the upper and lower extremities lead to excessive scarring and subsequent adhesion formation which, in turn, may result in severe pain and distinctly reduced range of motion. In revision surgery, replacement of the missing subcutaneous tissue is desirable to add volume and prevent new adhesions as well as to cushion scarred tendons and nerves and retain tissue elasticity. Therefore, the overall objective of this study was to evaluate collagen matrices regarding their suitabilty to serve as the basis for the generation of a thin adipose tissue layer for the reconstruction of the subcutaneous tissue. Specific aims were a) to seed different collagen matrices with adipose-derived stem cells, b) to evaluate the cell-seeded matrices with regard to size and shape stability, and c) to analyze adipogenic differentiation in vitro.

Material and Methods: Human adipose-derived stem cells (ASC) were obtained from abdominal liposuctions of different femal donors and expanded in culture. Five different collagen matrices (Permacol, Strattice, Hypro-Sorb, Collagen Cell Carrier, and OptiMaix) were chosen and ASC were seeded onto discs of the matrices (diameter 5 mm) at varying densities. Size and shape stability in culture medium was assessed without cells and after cell seeding. The most promising cell-matrix constructs with regard to seeding and stability were induced to undergo adipogenesis. Adipogenic differentiation was assessed by histological staining, triglyceride quantification and qRT-PCR gene expression analysis after culture for up to 14 days.

Results: With regard to maintenance of size and shape of the cell carriers, only the Permacol matrix completely remained stable after cell seeding and 14 days in culture. When seeded with 300,000 cells, only two collagen matrices, that is Permacol and Strattice, obtained the desired coherent multilayer of ASC on top of the matrix. After adipogenic induction, on these matrices the triclyceride content was demonstrated to substantially increase over time during 14 days of culture. Interestingly, both matrices exhibited even slight self-inducing properties without exogenous adipogenic stimuli. Adipogenesis was also reflected on the molecular level by increased mRNA expression of the adipogenic transcription factors PPARγ and C/EBPβ and further adipogenic markers, such as aP2 and Glut4. Results were consistent for various donors investigated.

Discussion: Of all matrices, only Permacol exhibited complete size and shape stability, which is likely due to the chemical cross-linking in the production of the porcine collagen matrix. The stability, which represents a major advantage for clinical handling, and the development of a thin adipose tissue layer on top of the matrix renders especially Permacol promising for the use as a cushioning layer after complex injuries involving large scar formation. Future investigations will evaluate the cell-matrix constructs in an in vivo model.