Functional Properties Of Extracellular Matrix Research Articles

Engineering cryoelectrospun elastin-alginate scaffolds to serve as stromal extracellular matrices

Scaffold-based regenerative strategies that emulate physical, biochemical, and mechanical properties of the native extracellular matrix (ECM) of the region of interest can influence cell growth and function. Existing ECM-mimicking scaffolds, including nanofiber (NF) mats, sponges, hydrogels, and NF-hydrogel composites are unable to simultaneously mimic typical composition, topography, pore size, porosity, and viscoelastic properties of healthy soft-tissue ECM. In this work, we used cryoelectrospinning to fabricate 3D porous scaffolds with minimal fibrous backbone, pore size and mechanical properties similar to soft-tissue connective tissue ECM. We used salivary glands as our soft tissue model and found the decellularized adult salivary gland (DSG) matrix to have a fibrous backbone, 10–30 μm pores, 120 Pa indentation modulus, and ∼200 s relaxation half time. We used elastin and alginate as natural, compliant biomaterials and water as the solvent for cryoelectrospinning scaffolds to mimic the structure and viscoelasticity of the connective tissue ECM of the DSG. Process parameters were optimized to produce scaffolds with desirable topography and compliance similar to DSG, with a high yield of >100 scaffolds/run. Using water as solvent, rather than organic solvents, was critical to generate biocompatible scaffolds with desirable topography; further, it permitted a green chemistry fabrication process. Here, we demonstrate that cryoelectrospun scaffolds (CESs) support penetration of NIH 3T3 fibroblasts 250–450 µm into the scaffold, cell survival, and maintenance of a stromal cell phenotype. Thus, we demonstrate that elastin-alginate CESs mimic many structural and functional properties of ECM and have potential for future use in regenerative medicine applications.

Collagen Extracts Derived From Young and Aged Mice Demonstrate Different Structural Properties and Cellular Effects in Three-Dimensional Gels

Three-dimensional (3D) type I collagen gels are increasingly utilized to simulate extracellular matrix (ECM) in vivo, but little is known about the effects of age on this model. Collagen was extracted from young (4-6 months) and aged (20-24 months) mice tails and compared. The collagens appeared similar by electrophoresis. However, relative to young, aged collagen formed fibrils slower and generated 3D gels with smaller diameter, less dense fibrils (75 vs 34 nm diameter and 8 vs 3.5% area, for young and aged respectively, p < 0.02). Correspondingly, aged collagen gels were more malleable and contractible (5% vs 19% compression, p < .02, and 73% vs 15.5% area, p < .01, for young and aged, respectively). Fibroblasts cultured within young and aged collagen gels had differential expression of a limited number of genes and proteins corresponding to specific integrins and matrix components. In summary, collagen extracted from young and aged mice is an effective means to examine the influence of aging on functional properties of ECM that are relevant in vivo.