Abstract: The invention features a method for generating new tissue by obtaining a liquid hydrogel-cell composition including a hydrogel and tissue precursor cells; delivering the liquid hydrogel-cell composition into a permeable, biocompatible support structure; and allowing the liquid hydrogel-cell composition to solidify within the support structure and the tissue precursor cells to grow and generate new tissue. The invention also features a tissue forming structure including a permeable, biocompatible support structure having a predetermined shape that corresponds to the shape of desired tissue; and a hydrogel-cell composition at least partially filling the support structure, wherein the hydrogel-cell composition includes a hydrogel and tissue precursor cells. The new tissue forming structure can be used in new methods to generate various tissues (e.g., to treat defective tissue) including new bone, cartilage, and nervous tissue such as spinal cord tissue. The invention also new isolated nervous system stem cells.

Abstract: Connective tissue, including neo-tendons and ligaments, has been constructed using biodegradable synthetic scaffolds seeded with tenocytes. The scaffolds are preferably formed from biodegradable fibers formed of a polymer such as polyglycolic acid-polylactic acid copolymers, and seeded with cells isolated from autologous tendon or ligament by means of enzymatic digestion or direct seeding into tissue culture dishes from explants. The cell polymer constructs are then surgically transplanted to replace missing segments of functioning tendon or ligament.

Abstract: The invention features a method for generating new tissue, the method including: obtaining a liquid hydrogel-cell composition including a hydrogel and tissue precursor cells; delivering the liquid hydrogel-cell composition into a permeable, biocompatible support structure; and allowing the liquid hydrogel-cell composition to solidify within the support structure and the tissue precursor cells to grow and generate new tissue. The invention also features a tissue forming structure including: a permeable, biocompatible support structure having a predetermined shape that corresponds to the shape of desired tissue; and a hydrogel-cell composition at least partially filling the support structure, wherein the hydrogel-cell composition comprises a hydrogel and tissue precursor cells.

Abstract: The invention provides compositions and methods for generating new tissue on a surface, e.g., a surface of damaged or lost tissue, of a structure or organ in a mammal, The methods involve applying a thin layer of a liquid hydrogel-cell composition to the surface; and allowing the liquid hydrogel-cell composition to solidify, thereby forming a matrix that enables the tissue precursor cells to grow and generate new tissue. The surface can be internal, e.g., the surface of an organ or the internal surface of a blood vessel, or external, e.g., skin.

Abstract: Methods and artificial matrices for the growth and implantation of cartilaginous structures and surfaces and bone are disclosed. In the preferred embodiments, chondrocytes are grown on biodegradable, biocompatible fibrous polymeric matrices. Optionally, the cells are proliferated in vitro until an adequate cell volume and density has developed for the cells to survive and proliferate in vivo. One advantage of the matrices is that they can be cast or molded into a desired shape, on an individual basis, so that the final product closely resembles a patient's own ear or nose. Alternatively, flexible matrices can be used which can be manipulated at the time of implantation, as in a joint, followed by remodeling through cell growth and proliferation in vivo. The cultured cells can also be maintained on the matrix in a nutrient media for production of bioactive molecules such as angiogenesis inhibiting factor.

Abstract: A cell-polymeric solution is injected into an animal where the polymer crosslinks to form a polymeric hydrogel containing dispersed cells and the cells form new tissue in the animal. The polymer is biodegradable and is a natural polymer such as alginate or a synthetic polymer. The cells are chondrocytes, osteoblasts, muscle cells, fibroblasts or cells acting primarily to synthesize, secret or metabolize materials. Crosslinking of the polymer results from using cations or anions, altering the pH or changing the temperature. A polyion such as polyethyleneimine or polylysine can be added before injection to stabilize the polymeric hydrogel. A kit for tissue formation is provided by combining the cell-polymeric solution with a means for injecting the solution into an animal.

Abstract: Methods and artificial matrices for the growth and implantation of cartilaginous structures and surfaces are disclosed. In the preferred embodiments, chondrocytes are grown on biodegradable, biocompatible fibrous polymeric matrices. Optionally, the cells are proliferated in vitro until an adequate cell volume and density has developed for the cells to survive and proliferate in vivo. One advantage of the matrices is that they can be cast or molded into a desired shape, on an individual basis, so that the final product closely resembles a patient's own ear or nose. Alternatively, flexible matrices can be used which can be manipulated at the time of implantation, as in a joint, followed by remodeling through cell growth and proliferation in vivo. The cultured cells can also be maintained on the matrix in a nutrient media for production of bioactive molecules such as angiogenesis inhibiting factor.