Marrow stromal cells (MSCs) have been suggested as a means to improve healing in tendon
overuse injuries (
tendinopathy), but optimal delivery methods for these cells have yet to be determined. In this study novel degradable
hydrogels based on
oligo(poly(ethylene glycol) fumarate) (OPF) and acrylated poly(
ethylene glycol)-
dithiothreitol (Ac PEG-DTT) with tunable degradation times ranging from a few days to >1 month were synthesized as MSC carriers for tendon
overuse injuries. The addition of higher amounts of OPF or higher
dithiothreitol (DTT) concentrations resulted in enhanced fold swelling and degradation. Three formulations, including non-degrading, slower degrading (degraded in ∼10 days) and faster degrading (degraded in ∼5 days)
hydrogels were selected for studies with MSCs in tendon tissue explants that had been treated with
collagenase as a reproducible model of
tendinopathy. Quantitative analysis of the resulting histology images indicated that cell delivery from the
hydrogels was dependent on the degradation rate, with cells present in the tissue only after
hydrogel dissolution. In addition, significantly more cells were found in the tendon after 14 days with the fast degrading (53±19) vs. slow degrading (20±6)
hydrogels. Based on these results, OPF/Ac PEG-DTT
hydrogels provide a versatile
biomaterial platform to control cell delivery and thus better identify dosing regimens required for MSC-based
therapies for
tendinopathy.