Non-Newtonian Polymer-Nanoparticle Hydrogels Enhance Cell Viability during Injection

Drug delivery and cell transplantation require minimally invasive deployment strategies such as injection through clinically relevant high-gauge needles. Supramolecular hydrogels comprising dodecyl-modified hydroxypropylmethylcellulose and poly(ethylene glycol)-block-poly(lactic acid) have been previously demonstrated for the delivery of drugs and proteins. Here, it is demonstrated that the rheological properties of these hydrogels allow for facile injectability, an increase of cell viability after injection when compared to cell viabilities of cells injected in phosphate-buffered saline, and homogeneous cell suspensions that do not settle. These hydrogels are injected at 1 mL min^-1 with pressures less than 400 kPa, despite the solid-like properties of the gel when at rest. The cell viabilities immediately after injection are greater than 86% for adult human dermal fibroblasts, human umbilical vein cells, smooth muscle cells, and human mesenchymal stem cells. Cells are shown to remain suspended and proliferate in the hydrogel at the same rate as observed in cell media. The work expands on the versatility of these hydrogels and lays a foundation for the codelivery of drugs, proteins, and cells.