Bone marrow may be aspirated from the marrow cavity of bones, such as the tibia and iliac crest. In the conventional approach for engineering cartilage, tissue engineers isolate mesenchymal progenitors from the bone marrow using negative selection techniques. Mesenchymal stem cells are then plated, culture expanded and treated with growth factors to induce chondrogenic differentiation. This laborious process may take up to several weeks of laboratory manipulation. In the present approach, bone marrow progenitors may be directly added to a chondrogenic gel material that includes controlled delivery of chonrogenic factors such as TGFβ3 that promote chondrogenesis in situ or in vivo, circumventing laboratory cell manipulation and differentiation.