Researcher(s)
- Sarah Liu, Biomedical Engineering, University of Delaware
Faculty Mentor(s)
- Brian Kwee, Biomedical Engineering, University of Delaware
Abstract
Ischemia, the loss of blood flow as a result of injury or disease, affects millions of people per year. Ischemic muscle damage leads to muscle degeneration, denervation, and tissue necrosis. Amphiregulin (AREG) is an anti-inflammatory cytokine that stimulates muscle satellite cells, endothelial cells, and motor neurons to promote tissue repair after ischemic injury. We engineered an injectable, oxidized (degradable by hydrolysis), calcium cross-linked alginate hydrogel for sustained AREG delivery to ischemic injuries.
Hydrogels were formulated using very low and medium viscosity alginate, oxidized at low or high percentages, loaded with murine or human AREG, and crosslinked with calcium sulfate. In vitro experiments evaluated hydrogel degradation and AREG release. To assess degradation, hydrogels were collected immediately after fabrication (day 0) and on day 7, lyophilized, weighed, and analyzed for mass loss. AREG release from the hydrogel was quantified over 14 days using an enzyme-linked immunosorbent assay (ELISA). To evaluate efficacy in vivo, mice underwent hindlimb ischemia surgery followed by intramuscular administration of either a blank or AREG-loaded hydrogel. 14 days post-injury, calf muscles were harvested, fixed in 4% paraformaldehyde, cross-sectioned, stained for laminin, and imaged at 20x magnification. Muscle fiber cross-sectional area was quantified using MyoAnalyst, which identified muscle fiber perimeters and calculated average fiber area.
Incorporation of AREG into the alginate hydrogel produced sustained release over 14 days for both murine and human proteins. Increasing alginate oxidation enhanced total AREG release and accelerated hydrogel degradation. AREG-treated muscles exhibited a trend toward larger average muscle fiber area and perimeter than blank hydrogel-treated muscle controls. Future studies will quantify cellular responses, evaluate gait recovery, and further characterize tissue regeneration following sustained AREG delivery.