The increase in the pore size of gelatin methacryloyl (GelMA) macroporous hydrogel promotes cell proliferation by enhancing substance permeability

Abstract

Gelatin methacryloyl (GelMA) hydrogels are widely used in tissue engineering because of their excellent biocompatibility, yet their dense network structure restricts substance transport and limits cell proliferation. Although the introduction of macroporous structures can alleviate this problem, most existing studies are limited to qualitative descriptions of permeability, lacking a quantitative framework to characterize the substance transport efficiency in such hydrogel networks and to study their impact on cell proliferation. In this work, we fabricated a series of GelMA macroporous hydrogels with tunable pore sizes through liquid–liquid phase separation (LLPS) combined with photopolymerization. The influence of pore size on the permeability of model solutes with different molecular weights was systematically investigated. Based on the classical analytical solution of Fick's second law, a quantitative diffusion model was established to determine the effective diffusion coefficient (D_eff) of each solute in hydrogels with varying pore structures. A power-law relationship between the normalized diffusion coefficient and pore size was further constructed. The results indicated that for the same solute, its relative diffusion capacity exhibits a nonlinear increase with increasing pore size, indicating that larger pores significantly enhance permeability. Among different solutes, macromolecular solutes displayed significantly higher sensitivity to pore size variations compared to small molecules. In vitro studies with bone marrow mesenchymal stem cells (BMSCs) suggest that enhanced permeability facilitates glucose uptake and ATP production, consistent with the observed vigorous cell proliferation. This study offers insights into the quantitative correlation between pore architecture, substance transport, and cellular responses, providing a theoretical basis for designing hydrogel scaffolds with optimized microenvironments.