Injectable Collagen–Genipin Gel for the Treatment of Spinal Cord Injury: In Vitro Studies

Abstract

Spinal cord injury (SCI) often results in a cavitary lesion, contained within the dura, which involves only a portion of the cord. Injectable biopolymers are an attractive treatment option for SCI to re‐establish cell migratory pathways within the lesion while minimizing the collateral damage attendant to an open surgical procedure. In this study we evaluate a thermoresponsive soluble collagen gel incorporating genipin, an amine reactive covalent cross‐linker with low cytotoxicity and fluorogenic attributes. Unlike previous studies, genipin is being investigated as an in situ covalent cross‐linker that will continue to act on the gel after injection. Physical characterization studies show that the addition of genipin provides control over the mechanical and degradative behavior of the gel, to meet design specifications of an injectable material for neural tissues. Additionally, an improved in situ assay to predict the extent of cross‐linking reaction is investigated. Encapsulation of mesenchymal stem cells (MSCs) in collagen–genipin gels show the gels support cell viability and proliferation, and thus serve as a cell delivery vehicle. Neural stem cells are found to be more sensitive to genipin, with respect to toxicity, as compared to MSCs. From our studies, 0.25‐0.5 mM is an appropriate genipin concentration to use for an in situ forming scaffold capable of delivering cells and therapeutic agents.

Dual crosslinking strategy to generate mechanically viable cell-laden printable constructs using methacrylated collagen bioinks

“…Results from the AlamarBlue cell metabolic assay displayed a similar trend (Figure 7), showing a significant decrease (p < 0.05) in the metabolic activity on high genipin crosslinked cell-laden CMA hydrogels. These results are consistent with the findings reported by Macaya et al who showed that exposure to 1 mM genipin resulted in a significant decrease in cell viability (i.e., < 60%) [15]. On the other hand, Kim et al showed that cell viability in encapsulated hydrogels remains greater than 90% even at 3 mM genipin concentrations after 1 hour [23].…”

Biopolymer-based hydrogels as injectable materials for tissue repair scaffolds

“…As expected, the microviscosity determined for the hydrogels obtained after a longer maturation time (24 h) were higher in comparison to those determined for the samples with shorter gelation time (1 h), although the same dependence on the genipin concentration is preserved. These differences reflect the fact that the completion of the crosslinking process requires more than 1 h, which is in agreement with the observation described earlier in the literature [26].…”

Genipin stabilized fibrin microbeads: Carrying cytokines to form niches for stem cell differentiation

“…As the results showed, 2 mg/mL genipin could crosslink SHH to gFMBs as efficiently as 4 mg/mL, suggesting the existence of saturation effects of genipin. Although the dose of genipin used to crosslink SHH to gFMBs was higher than those recommended by other studies, 43,44 no obvious toxicity of gFMBs@SHH (gp1, gp2, and gp4) was found in this study. The remnant free genipin after crosslinking might be washed away.…”