Self-assembled dodecyl group-modified gelatin microparticle-based hydrogels with angiogenic properties

Yosuke Mizuno,Tetsushi Taguchi

doi:10.1038/s41427-020-0229-4

Abstract

Supplying oxygen and nutrients to implanted cells or tissues is an important factor that improves their survivability and function in regenerative medicine. Various efforts have been made to develop angiogenic materials by incorporating and releasing growth factors such as vascular endothelial growth factor (VEGF). However, these exogenous growth factors have a short half-life under physiological conditions. We therefore designed a novel angiogenic microparticle (C12-MP) comprising Alaska pollock-derived gelatin (ApGltn) modified with a dodecyl group (C12-ApGltn) to stimulate endogenous VEGF secretion. The C12-MP suspension formed an injectable hydrogel, the rheological properties and enzymatic degradation of which were evaluated. RAW264 cells, mouse macrophage-like cells, cultured with C12-MPs, secreted significantly more VEGF than the original ApGltn MPs. Based on laser Doppler perfusion imaging, the C12-MP hydrogel clearly induced increased blood perfusion in a subcutaneous mouse model compared with the original ApGltn microparticle (Org-MP) or phosphate-buffered saline controls. Histological studies revealed that the areas of nuclear factor (NF)-κB, CD31, and myeloperoxidase staining showed a greater increase at the site injected with C12-MPs than at the site injected with the original ApGltn microparticles or phosphate-buffered saline. The C12-MP hydrogel is a promising angiogenic material for constructing vascular beds for cell transplantation by promoting endogenous VEGF secretion without additional growth factors.

Highlights

Angiogenesis is necessary for the proliferation of implanted cells or tissues to supply oxygen and nutrients from host tissue
We reported that a dodecyl group-modified (C12) Alaska pollock-derived gelatin (ApGltn) (C12-ApGltn), which mimics an LPS of Pseudomonas aeruginosa (Fig. 1a), formed a self-assembled hydrogel that stimulated vascular endothelial growth factor (VEGF) secretion in vitro and in vivo through toll-like receptor 4 (TLR4)-mediated pathways[17]
Collagenase, water-soluble tetrazolium (WST)-8 reagent (Cell Count Reagent SF) and Dulbecco’s phosphate-buffered saline (PBS) were obtained from Nacalai Tesque (Kyoto, Japan). 2,4,6-Trinitrobenzenesulfonic acid (TNBS), triethylamine, 2-aminoethanol, ethanol, dimethyl sulfoxide (DMSO), and 10% formalin neutral buffer solution were purchased from Wako Pure Chemical Industries (Osaka, Japan)

Summary

Introduction

Angiogenesis is necessary for the proliferation of implanted cells or tissues to supply oxygen and nutrients from host tissue. This hydrogel induced microvascular formation around the implant site by the released VEGF and KGF These growth factors effectively promote angiogenesis, their instability under physiological conditions is considered a limitation to their practical application[3] because VEGF and fibroblast growth factor-2 (FGF-2) have half-lives of only 50 and 9.6 min, respectively[4,5]. To overcome these problems, we focused on the use of endogenous growth factors to achieve angiogenesis. Proangiogenic growth factors such as VEGF are mainly secreted from macrophages in response to ischemia, injury, and inflammation[6]

Methods

Results

Conclusion