Mechanobiology of mesenchymal stem cells and their use in cardiovascular repair.

Mesenchymal stem cells (MSCs) derived from bone marrow have shown great promise in tissue repair. While these cells induce little immune response, they show marked self-renewal properties and can differentiate into many cell types. Recent evidence shows that mechanical factors such as fluid shear stress, mechanical strain and the rigidity of extracellular matrix can regulate the proliferation and differentiation of MSCs through various signaling pathways. Transplanted MSCs enhance angiogenesis and contribute to remodeling of the vasculature. In this review, we will focus on the responses of vascular cells and MSCs to shear stress, strain and matrix rigidity and will discuss the use of MSCs in myocardial repair and vascular tissue engineering.

The effect of fiber alignment and heparin coating on cell infiltration into nanofibrous PLLA scaffolds.

Biodegradable nanofibers simulate the fibril structure of natural extracellular matrix, and provide a cell-friendly microenvironment for tissue regeneration. However, the effects of nanofiber organization and immobilized biochemical factors on cell infiltration into three-dimensional scaffolds are not well understood. For example, cell infiltration into an electrospun nanofibrous matrix is often limited due to relatively small pore size between the fibers. Here we showed that biophysical and biochemical modification of nanofibrous scaffolds facilitated endothelial cell infiltration in three-dimensional scaffolds in vitro and in vivo. Aligned nanofibers significantly enhanced cell infiltration into the nanofibrous matrices in vitro. In a full-thickness dermal wound model, the nanofiber scaffolds enhanced epidermal skin cell migration across the wound when compared to a control group without scaffold. Aligned nanofibers promoted the infiltration of endothelial cells into the scaffolds. Furthermore, heparin-coated nanofibers also increased cell infiltration significantly. These results shed light on the importance of biophysical and biochemical properties of nanofibers in the regulation of cell infiltration into three-dimensional scaffolds and tissue remodeling.

Designation of the TARP syndrome and linkage to Xp11.23-q13.3 without samples from affected patients.

The Robin sequence is a well-known cause of cleft palate and can be sporadic or familial, isolated or syndromic. We present a four-generation family with a lethal disorder inherited in an X-linked recessive pattern that includes Talipes equinovarus, Atrial septal defect, Robin sequence, and Persistence of the left superior vena cava. We have designated this disorder "TARP" syndrome. All affected males die in infancy of unknown causes. An X-chromosome linkage scan was performed using 14 unaffected members of a single large family and 40 STRP markers. The gene was mapped to an 11-cM region in Xp11.23-q13.3. Markers DXS1003 and DXS8092 flank the region and three-point linkage analyses revealed a maximum LOD score of 2.75 at marker DXS1039. We have designated this locus as TARP. This locus was mapped without genotyping any affecteds and demonstrates that rare, lethal disorders can be evaluated by genetic linkage, even when no affected probands are available for study.