Effect of pore size and void fraction on cellular adhesion, proliferation,and matrix deposition

The aim of this study was to determine the influence of two key scaffold de sign parameters, void fraction (VF) and pore size, on the attachment, growt h, and extracellular matrix deposition by several cell types. Disc-shaped, porous, poly(L-lactic acid) (L-PLA) scaffolds were manufactured by the Ther iForm(TM) solid free-form fabrication process to generate scaffolds with tw o VF (75% and 90%) and four pore size distributions (<38, 38-63, 63-106, an d 106-150 <mu>m). Microcomputed tomography analysis revealed that the avera ge pore size was generally larger than the NaCl used, while VF was at or ne ar the designated percentage. The response of three cell types-canine derma l fibroblasts (DmFb), vascular smooth muscle cells (VSMC), or microvascular epithelial cells (MVEC)-to variations in architecture during a 4-week cult ure period were assessed using histology, metabolic activity, and extracell ular matrix deposition as comparative metrics. DmFb, VSMC, and MVEC showed uniform seeding on scaffolds with 90% VF for each pore size, in contrast to the corresponding 75% VF scaffolds. DmFb showed the least selectivity for pore sizes. VSMC displayed equivalent cell proliferation and matrix deposit ion for the three largest pore sizes. MVEC formed disconnected webs of tiss ue with sparse extracellular matrix at 90% VF and >38 to 150 mum; however, when cultured on scaffolds with pores formed with salt particles of <38 <mu >m, MVEC formed a multilayered lining on the scaffolds surface. Culture dat a from scaffolds with a 75% VF suggests that the structural features were u nsuitable for tissue formation. Hence, there were limits of acceptable scaf fold architecture (VF, pore size) that modulated in vitro cellular response s.