Bone with a vascular flap induced from fat tissue with the use of rhBMP-2 in rats

Molded vascularized neo-ossicle formation in silicone chambers

Vascularized bone grafts generally achieve their aims but are not used frequently owing to donor site morbidity and limited supply. To bioengineer an alternate vascularized bone graft, we developed a novel silicone bone reactor capable of producing vascularized neo-ossicles when appropriate osteoprecursor elements are included in the implanted chambers. Requirements for ossicle production were assessed in the model, including osteoprogenitor cells (donor bone marrow), osteoinductive signals (rhBMP2 or demineralized bone matrix), and osteoconductive matrix (Collagraft). Ossicle production required patency of the vascular pedicle, and for samples not containing cancellous isograft, donor marrow viability and an osteoinductive signal. Ossicles were produced without the need for an implanted osteoinductive matrix. Bone production and maturation time course were similar in chambers containing cancellous isograft, marrow/rhBMP2, and marrow/demineralized bone matrix. The demineralized bone matrix group had delayed early bone production, and the rhBMP2 group had lower final bone area. All groups had central osteolysis in the vascularized neo-ossicles. We believe the approach is promising for selected applications.

Collagenous microbeads as a scaffold for tissue engineering with adipose-derived stem cells

BACKGROUND

Standard approaches to soft-tissue reconstruction include autologous tissue flaps and alloplastic implants. Both of these approaches have disadvantages, including donor-site morbidity, implant migration, and foreign body reaction. Autologous fat transplantation, with a minimally invasive cannula harvest, has lower donor-site morbidity than tissue flaps do, but there is an unpredictable degree of resorption of the transplanted fat over time. Adipose-derived stem cells isolated from harvested fat are better able to withstand the mechanical trauma from the suction cannula and may allow for improved cell survival and generation of new fat tissue after transfer to another anatomic site. The authors hypothesized that porous collagenous microbeads (CultiSphers; Sigma, St. Louis, Mo.) could be useful as injectable cell delivery vehicles for adipose-derived stem cells. This strategy would allow induction of differentiation ex vivo and precise placement of cells and scaffold in a tissue bed. The objective of this study was to assess the ability of the stem cells to proliferate and differentiate on these microbeads.

METHODS

Adipose-derived stem cells were isolated from discarded human adipose tissue and cultured on porous collagenous microbeads in a stirred bioreactor (spinner flask). The cells attached and proliferated on the microbeads and maintained high viability over several weeks of culture.

RESULTS

When exposed to adipogenic or osteogenic medium, the cells differentiated into adipocytes and osteoblasts, respectively, while attached to the microbeads.

CONCLUSION

Collagenous microbeads are a favorable scaffold for adipose-derived stem cells, allowing ex vivo proliferation and differentiation on particles that are small enough to be injected.

Gene-enhanced tissue engineering for dental hard tissue regeneration: (1) overview and practical considerations

Gene-based therapies for tissue regeneration involve delivering a specific gene to a target tissue with the goal of changing the phenotype or protein expression profile of the recipient cell; the ultimate goal being to form specific tissues required for regeneration. One of the principal advantages of this approach is that it provides for a sustained delivery of physiologic levels of the growth factor of interest.

This manuscript will review the principals of gene-enhanced tissue engineering and the techniques of introducing DNA into cells. Part 2 will review recent advances in gene-based therapies for dental hard tissue regeneration, specifically as it pertains to dentin regeneration/pulp capping and periodontal regeneration.