Dendrimer cross-linking has been achieved with pepsin digested over 80% type-I bovine collagen to create strong hydrogels with good cell compatibility. Herein we investigate the use of commercially available collagen-based products with the dendrimer cross-linking technology. Specifically PureCol(®) (PC), a 97% bovine type-I collagen, human collagen (HC) and human extracellular matrix (hECM) were concentrated, and then cross-linked with polypropyleneimine octaamine generation two dendrimers using 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) chemistry. PC gels with 30 and 20 mg/ml bovine collagen were fabricated, and despite similar concentrations to >80% type-I bovine collagen dendrimer cross-linked gels (CG), PC gels demonstrated increased swelling and decreased stability, as determined with collagenase digestion. The highly purified bovine (PC) and human sourced-collagen (HC) gels were similar in performance, but not as stable as the CG gels, which may correlate to the manufacturer's collagen purification and storage. Finally, the addition of hECM components to PC to create PC-hECM gels, resulted in a looser gel network, compared to heparinized dendrimer cross- linked bovine >80% type-I collagen gels (CHG). However, all collagen-based gels supported 3T3 fibroblast cell growth over 4 days, indicating these gels may be suitable for tissue-engineering applications.
