Osteoinduction in umbilical cord- and palate periosteum-derived mesenchymal stem cells.

Adult abdominoplasty (AA) fat is an ideal source for mesenchymal stem cells (MSCs) because it is discarded after surgery, abundant, and easy to harvest. Children however, do not have the same abundant quantities of fat as adults, nor are they likely to undergo a procedure during which fat is routinely discarded. Hence, finding an alternate source for MSCs in children is a reasonable strategy. Two such sources are the palate periosteum (PP) and the umbilical cord (UC). Advantages for PP as a source of MSCs are accessibility during palate repair, ease of harvest, and minimal risk to the patient. The UC, like AA, is a discarded tissue, with a theoretically unlimited supply, which can be harvested in children with craniofacial bone abnormalities in advance of reconstructive procedures. Our objective in this study is to characterize MSCs from 3 sources (AA, PP, and UC) by surface marker prevalence, and to assess osteoinductive capability. Institutional review board approval was obtained for harvest of AA, PP, and UC. The presence of MSCs was determined using immunostaining and flow cytometry for cell surface markers CD73, CD90, CD105, and SSEA-4. Osteogenesis was induced using osteogenic medium. Osteoinduction was evaluated using Alizarin red staining, and real-time polymerase chain reaction for bone morphogenetic protein-2, alkaline phosphatase, and osteocalcin at 7, 14, and 21 days. MSCs from AA, PP, and UC all stained positive for CD73, CD90, CD105, and SSEA-4. Flow cytometry demonstrated significant differences in expression of CD90 and SSEA-4 but similar values for CD73 and CD105. Following osteoinduction, MSCs from all sources stained positive for calcium deposition. In UC MSCs, reverse transcriptase-polymerase chain reaction demonstrated greater elevation in bone morphogenetic protein-2 and alkaline phosphatase mRNA beginning at day 7 and extending to day 21. Osteocalcin mRNA levels were comparable for all 3 sources of MSCs. For children with craniofacial bone defects, UC-derived MSCs may be ideal for tissue engineered bone: temporally, the UC can be harvested in advance of surgical timing for the need for bone, is readily available, easy to harvest, and leads to osteoinduction that is more robust than either AA or PP.

Composite tissue engineering on polycaprolactone nanofiber scaffolds.

Tissue engineering has largely focused on single tissue-type reconstruction (such as bone); however, the basic unit of healing in any clinically relevant scenario is a compound tissue type (such as bone, periosteum, and skin). Nanofibers are submicron fibrils that mimic the extracellular matrix, promoting cellular adhesion, proliferation, and migration. Stem cell manipulation on nanofiber scaffolds holds significant promise for future tissue engineering. This work represents our initial efforts to create the building blocks for composite tissue reflecting the basic unit of healing. Polycaprolactone (PCL) nanofibers were electrospun using standard techniques. Human foreskin fibroblasts, murine keratinocytes, and periosteal cells (4-mm punch biopsy) harvested from children undergoing palate repair were grown in appropriate media on PCL nanofibers. Human fat-derived mesenchymal stem cells were osteoinduced on PCL nanofibers. Cell growth was assessed with fluorescent viability staining; cocultured cells were differentiated using antibodies to fibroblast- and keratinocyte-specific surface markers. Osteoinduction was assessed with Alizarin red S. PCL nanofiber scaffolds supported robust growth of fibroblasts, keratinocytes, and periosteal cells. Cocultured periosteal cells (with fibroblasts) and keratinocytes showed improved longevity of the keratinocytes, though growth of these cell types was randomly distributed throughout the scaffold. Robust osteoinduction was noted on PCL nanofibers. Composite tissue engineering using PCL nanofiber scaffolds is possible, though the major obstacles to the trilaminar construct are maintaining an appropriate interface between the tissue types and neovascularization of the composite structure.

Cellular incorporation into electrospun nanofibers: retained viability, proliferation, and function in fibroblasts.

Nanofibers are an emerging scaffold for tissue engineering. To date no one has reported cell incorporation into nanofibers. Human foreskin fibroblasts and human adipose-derived adult stem cells (hADAS) were grown to confluence, resuspended in phosphate-buffered saline, and then solubilized in polyvinyl alcohol (PVA). Nanofibers were created using an electrospinning technique across an electric potential of 20 kV. Cell interaction with nanofibers was assessed with optical microscopic imaging and scanning electron microscopy. PVA nanofibers with incorporated cells were then solubilized in phosphate-buffered saline; cell viability was assessed by trypan blue exclusion. Viable cells were allowed to proliferate. Chondrogenesis in fibroblasts was induced with TGF-beta1. Both fibroblasts and hADAS survived the electrospinning process and were incorporated into PVA nanofibers. hADAS cell proliferation was negligible; however, fibroblasts proliferated and showed retained ability to undergo chondrogenesis. Cells can be incorporated into nanofibers, with maintained viability, proliferation, and function.