Injectable pulverized electrospun poly(lactic-co-glycolic acid) fibers improve human adipose tissue engraftment and volume retention.

Autologous adipose tissue is commonly used for tissue engraftment for the purposes of soft tissue reconstruction due to its relative abundance in the human body and ease of acquisition using liposuction methods. This has led to the adoption of autologous adipose engraftment procedures that allow for the injection of adipose tissues to be used as a "filler" for correcting cosmetic defects and deformities in soft tissues. However, the clinical use of such methods has several limitations, including high resorption rates and poor cell survivability, which lead to low graft volume retention and inconsistent outcomes. Here, we describe a novel application of milled electrospun poly(lactic-co-glycolic acid) (PLGA) fibers, which can be co-injected with adipose tissue to improve engraftment outcomes. These PLGA fibers had no significant negative impact on the viability of adipocytes in vitro and did not elicit long-term proinflammatory responses in vivo. Furthermore, co-delivery of human adipose tissue with pulverized electrospun PLGA fibers led to significant improvements in reperfusion, vascularity, and retention of graft volume compared to injections of adipose tissue alone. Taken together, the use of milled electrospun fibers to enhance autologous adipose engraftment techniques represents a novel approach for improving upon the shortcomings of such methods.

Early Intervention in Ischemic Tissue with Oxygen Nanocarriers Enables Successful Implementation of Restorative Cell Therapies.

BACKGROUND: Tissue ischemia contributes to necrosis and infection. While angiogenic cell therapies have emerged as a promising strategy against ischemia, current approaches to cell therapies face multiple hurdles. Recent advances in nuclear reprogramming could potentially overcome some of these limitations. However, under severely ischemic conditions necrosis could outpace reprogramming-based repair. As such, adjunctive measures are required to maintain a minimum level of tissue viability/activity for optimal response to restorative interventions. METHODS: Here we explored the combined use of polymerized hemoglobin (PolyHb)-based oxygen nanocarriers with Tissue Nano-Transfection (TNT)-driven restoration to develop tissue preservation/repair strategies that could potentially be used as a first line of care. Random-pattern cutaneous flaps were created in a mouse model of ischemic injury. PolyHbs with high and low oxygen affinity were synthesized and injected into the tissue flap at various timepoints of ischemic injury. The degree of tissue preservation was evaluated in terms of perfusion, oxygenation, and resulting necrosis. TNT was then used to deploy reprogramming-based vasculogenic cell therapies to the flaps via nanochannels. Reprogramming/repair outcomes were evaluated in terms of vascularity and necrosis. RESULTS: Flaps treated with PolyHbs exhibited a gradual decrease in necrosis as a function of time-to-intervention, with low oxygen affinity PolyHb showing the best outcomes. TNT-based intervention of the flap in combination with PolyHb successfully curtailed advanced necrosis compared to flaps treated with only PolyHb or TNT alone. CONCLUSIONS: These results indicate that PolyHb and TNT technologies could potentially be synergistically deployed and used as early intervention measures to combat severe tissue ischemia.

Nanochannel-Based Poration Drives Benign and Effective Nonviral Gene Delivery to Peripheral Nerve Tissue.

While gene and cell therapies have emerged as promising treatment strategies for various neurological conditions, heavy reliance on viral vectors can hamper widespread clinical implementation. Here, the use of tissue nanotransfection as a platform nanotechnology to drive nonviral gene delivery to nerve tissue via nanochannels, in an effective, controlled, and benign manner is explored. TNT facilitates plasmid DNA delivery to the sciatic nerve of mice in a voltage-dependent manner. Compared to standard bulk electroporation (BEP), impairment in toe-spread and pinprick response is not caused by TNT, and has limited to no impact on electrophysiological parameters. BEP, however, induces significant nerve damage and increases macrophage immunoreactivity. TNT is subsequently used to deliver vasculogenic cell therapies to crushed nerves via delivery of reprogramming factor genes Etv2, Foxc2, and Fli1 (EFF). The results indicate the TNT-based delivery of EFF in a sciatic nerve crush model leads to increased vascularity, reduced macrophage infiltration, and improved recovery in electrophysiological parameters compared to crushed nerves that are TNT-treated with sham/empty plasmids. Altogether, the results indicate that TNT can be a powerful platform nanotechnology for localized nonviral gene delivery to nerve tissue, in vivo, and the deployment of reprogramming-based cell therapies for nerve repair/regeneration.