PAPER 007: DEVELOPMENT OF A GENIPIN CROSS-LINKED AUTOLOGOUS HUMAN FIBRIN GLUE SCAFFOLD FOR IN VITRO ARTICULAR CARTILAGE REGENERATION

Abstract

Purpose: The objective of this project is to evaluate the human fibrin glue, CryoSeal^®, as a scaffold for articular cartilage tissue engineering. An autologous system would eliminate risks associated with biocompatibility and virus transmission.

Method: Human articular chondrocytes were isolated from articular cartilage harvested from consenting patients undergoing total knee arthroplasty. The cells were encapsulated into CryoSeal^® fibrin glue – which is derived from a single patient’s plasma using the Cryo-Seal^® Fibrin Sealant System (Thermogenesis Corp.) – and cross-linked with genipin, which is a natural cross-linking agent with anti-inflammatory activity. The resulting gels were cultured in vitro for up to 7 weeks under either normal (21%) or low oxygen (5%) conditions and were evaluated for mechanical properties, extracellular matrix (ECM) production, viability, and biodegradation. Fibrin glue components were isolated from either fresh or frozen plasma.

Results: The dynamic compression modulus of the genipin cross-linked fresh plasma (FSP) CryoSeal^® gels increased by ~4.4-fold over 5 weeks in culture. The glycosaminoglycan (GAG) content of the FSP gels increased by 4.7-fold over 5 weeks in low oxygen (LO) culture, which was 1.7-fold greater than in normal oxygen (NO) culture. The total collagen content of the FSP cultures increased by 6.0-fold over 5 weeks in LO culture, which was 2.2-fold greater than in NO culture. These changes in ECM were confirmed by histology (Alcian Blue) and immunostaining (to detect collagen II, collagen I, aggrecan, Sox9) of gel cryosections. After 5 weeks in LO culture the FSP CryoSeal^®-encapsulated chondrocytes expressed a 6.4 ± 1.1 fold increase in collagen II gene expression, which was 5.8 ± 1.0 fold greater than in NO cultures. In addition, chondrocyte viability within the FSP and frozen plasma (FZP) CryoSeal^® gels was ~90% at both 24 hours and 2 weeks after gelation. When fibrin hydrogels were implanted subcutaneously into rats it was found that inflammation was inhibited with increasing genipin and when the material origin was species-specific.

Conclusion: The CryoSeal^® fibrin gel system demonstrates promise for autologous human articular cartilage tissue engineering. An in vivo orthopaedic implantation model must be developed for further testing.