Operating curves to characterize the contraction of fibroblast-seeded collagen gel/collagen fiber composite biomaterials: effect of fiber mass.

Background: Collagen is a well-established and important biomaterial that could be used to help meet significant medical needs for various soft-tissue replacements. Many efforts to create engineered soft-tissue constructs by seeding cells within collagen gels have been hampered because constituent cells contract collagen gels over time, resulting in a construct that is only a fraction of the original size and that contains a cell population that has suffered a large degree of cell death. However, the presence of embedded short collagen fibers has been shown to significantly limit contraction and dramatically enhance permeability in fibroblast-seeded collagen gels.

Methods: Five volume fractions of short collagen fibers were embedded in fibroblast-seeded collagen gels. Collagen gel contraction (n > or = 4 for all groups) and cell viability (n > or = 3 for all groups) were examined after up to 2 weeks in culture.

Results: The present study demonstrated that increasing the volume fraction of short collagen fibers in fibroblast-seeded collagen gels correspondingly reduced the amount of gel contraction without negatively impacting cell viability after 2 weeks of culture. Furthermore, operating curves that describe the quantitative relationships between the contraction of fibroblast-seeded collagen gel/collagen fiber composite biomaterials, time in culture, and volume fraction of embedded fibers were obtained.

Conclusion: The resulting operating curves enable investigators to tailor initial fabrication procedures to ultimately yield cell-seeded collagen composites of specifically desired sizes-a critical step toward developing clinically useful engineered soft-tissue constructs.