Substrate mineralization stimulates focal adhesion contact redistribution and cell motility of bone marrow stromal cells

Abstract

Understanding the mechanisms of substrate based control of cell function is critical to the design of biomaterials. Cells interact with their extracellular matrix through cell adhesion contacts. We have previously described the self assembly of bone-like mineral onto an organic template and have shown that these biomimetic surfaces lead to an increased volume fraction of bone regenerated in vivo. In the present study, we compared the distribution of cell adhesion contacts, cell spreading, and cell motility of murine bone marrow stromal cells (BMSC) on mineralized vs. nonmineralized substrates. We developed a new approach for quantification of cell-material interactions and demonstrated that cell adhesion contacts on mineralized substrates were distributed throughout the cell surface contacting the substrate, whereas on nonmineralized substrates cell adhesion contacts were present near the cell periphery. We propose that mineralized substrates stimulate the predominant expression of fibrillar contacts, and nonmineralized substrates stimulate expression of focal adhesion contacts. Cell motility assays with colloidal gold demonstrated a statistically significant decrease in the average phagokinetic index of migrating cells on mineralized vs. nonmineralized substrates after 90 min of cell seeding. We propose that the physical-chemical properties of the substrate, altered by mineralization, cause expression of specific types of cell contacts and, as a result, modify molecular mechanisms responsible for cell spreading, motility, and possibly differentiation.

The development of non-viral gene-activated matrices for bone regeneration using polyethyleneimine (PEI) and collagen-based scaffolds

“…Cells directly interact with their surrounding matrix via focal adhesions [33,47,56] and cells respond to mechanical cues such as substrate stiffness via these focal adhesions. Leonova et al showed that the mineralisation of substrates stimulates focal adhesion and motility of MSCs [58]. It is suspected that the addition of nHa is resulting in the adherence of more cells than in the collagen alone and collagen-GAG scaffolds due to increased scope for focal adhesion because of the presence of nHa.…”

Connexin 43 as a signaling platform for increasing the volume and spatial distribution of regenerated tissue

“…Bone marrow stromal cells were isolated from the long bones of 5-week-old C57BL/6 mice (University of Michigan UCUCA approval #08633), as described (24). BMSCs mixed with ␣-MEM (Gibco Laboratories) enriched with 10% FBS (Gibco Laboratories) and 100 g/mL penicillin G plus 100 IU/mL streptomycin were plated at 30,000 cells/cm 2 at 37°C in 5% CO2.…”

Using polymeric materials to control stem cell behavior for tissue regeneration

“…Inorganic components, such as hydroxyapatite, can improve protein adsorption and subsequent cell adhesion (Akkouch et al, 2011; Dimitrievska et al, 2008; Leonova et al, 2006; Li et al, 2009; Venugopal et al, 2010; Zhao et al, 2006a). Mineralized polymer surfaces can also be used to provide sustained release of growth factors and genes (Luong et al, 2006; Luong et al, 2009; Murphy et al, 2000; Segvich and Kohn, 2009).…”