Stem cells

Biomaterial scaffolds provide a vehicle to differentiate stem cells by controlled exposure to proteins, adhesion peptides, and growth factors in a three-dimensional matrix. Hydrogels are biomaterials capable of absorbing large amounts of water, have tissue-like mechanical properties, and can encapsulate cells. We have recently demonstrated the ability to promote adult bone marrow-derived mesenchymal stem cell (MSC) differentiation to cartilage and bone in photopolymerizing hydrogels by incubating in the appropriate media conditions. Direct incorporation of growth factors or other biological factors into the scaffold is required for in vivo applications where there is no "media" containing the specific growth factors. Therefore, we aim to create an environment conducive to stem cell differentiation by manipulating scaffold properties and incorporating the desired biological signals.

Embryonic germ and stem cells are another potential cell source for tissue engineering and cell therapies but much less is known how to regulate their differentiation. Thus, another arm of the lab is dedicated to determining conditions for stem cell differentiation using simply biological cues, materials, and niche microenvironments with complex cues.

Biomaterials

Researchers are learning more about the mechanisms of cell-scaffold interactions and tissue development. This knowledge has provided the groundwork for synthesizing sophisticated scaffolds that are able to both provide more complex biological signals to the nascent tissue and respond specifically to the biological environment. Materials that can respond to cell behavior and their biological environment are described as intelligent or bioresponsive materials. When tissue formation reaches a critical level the scaffold can interfere with the new tissue extracellular matrix organization and even reduce the desired cell activities. Thus, a balance must be reached with tissue development and scaffold degradation rate. To this end, we are working on new materials that can degrade in response to tissue development and naturally occurring biopolymers whose degradation products can be incorporated into the new tissue.

Integration of the Synthetic and Biological World

Numerous barriers exist when applying technologies developed in vitro to the in vivo environment. For example, while investigators have been able to engineer cartilage, integration of the newly generated cartilage with surrounding native tissue in vivo remains a significant problem since cartilage has a dense, avascular extracellular matrix that impedes cell migration and healing. We are examining techniques to bond our synthetic materials to cartilage and soft tissues for integration of engineered cartilage and as a tissue adhesive for would repair, respectively