Protein-engineered hydrogels enhance the survival of induced pluripotent stem cell-derived endothelial cells for treatment of peripheral arterial disease

Abstract

A key feature of peripheral arterial disease (PAD) is damage to endothelial cells (ECs), resulting in lower limb pain and restricted blood flow. Recent preclinical studies demonstrate that the transplantation of ECs via direct injection into the affected limb can result in significantly improved blood circulation. Unfortunately, the clinical application of this therapy has been limited by low cell viability and poor cell function. To address these limitations we have developed an injectable, recombinant hydrogel, termed SHIELD (Shear-thinning Hydrogel for Injectable Encapsulation and Long-term Delivery) for cell transplantation. SHIELD provides mechanical protection from cell membrane damage during syringe flow. Additionally, secondary in situ crosslinking provides a reinforcing network to improve cell retention, thereby augmenting the therapeutic benefit of cell therapy. In this study, we demonstrate the improved acute viability of human induced pluripotent stem cell-derived endothelial cells (iPSC-ECs) following syringe injection delivery in SHIELD, compared to saline. Using a murine hind limb ischemia model of PAD, we demonstrate enhanced iPSC-EC retention in vivo and improved neovascularization of the ischemic limb based on arteriogenesis following transplantation of iPSC-ECs delivered in SHIELD.

Non‐Newtonian Polymer–Nanoparticle Hydrogels Enhance Cell Viability during Injection

“…Hydrogels are readily suited for biological applications because of their tissue‐like mechanical properties, high water content, biocompatibility, and stimuli‐responsiveness. In the field of drug delivery, hydrogels provide sustained and temporally controlled delivery of drugs in localized regions, reducing off‐target toxicity and increasing clinical efficacy …”

Injectable supramolecular polymer–nanoparticle hydrogels enhance human mesenchymal stem cell delivery

“…3 There are many challenges in the local delivery of stem cell therapeutics. 8,11,12 Hydrogels can increase local cell retention and engraftment at the injection site compared to traditional liquid injections or infusion by acting as local niches to physically hold cells in place. 9,10 Injected cells must also interact with the immune system.…”

“…17 The development of shear-thinning hydrogels has enabled quicker, less invasive administration procedures by injection through a needle. 12,13,20,[24][25][26] Hydrogels based on polymers exhibiting lower critical solution temperature (LCST) behavior that are injectable liquids at room temperature but gel in situ at physiological temperature after injection have been developed 13,20,24 ; however, these "thermogelling" hydrogels can be difficult to handle due to their inherent temperature sensitivity, often involve harsh complex chemistries, and often suffer from cells settling in the syringe prior to injection. 19,23 However, injectable shearthinning hydrogels are often formed through weak physical interactions and cannot persist long enough in the body to enhance cell retention compared to traditional liquid injections.…”

“…The syringe containing the HPMC-C12 polymer was then attached to the elbow other end of the elbow. The two solutions were then mixed gently back and forth through the elbow for 30 s to 1 min until the solutions had completely mixed and formed a homogenous cell-loaded PNP hydrogel.…”

“…The leading methods for local delivery involve hydrogels, which are biomimetic water swollen polymer networks that are capable of suspending cells in 3D. 8,11,12 Hydrogels can increase local cell retention and engraftment at the injection site compared to traditional liquid injections or infusion by acting as local niches to physically hold cells in place. 13 Additionally hydrogels can act as immunomodulatory protective barriers against infiltrating immune cells.…”