U.S. Pat. No. 5,306,305 (=WO 95/19152) discloses an in vitro method for producing an implant device by coating a gel containing osteoblast cells onto a porous metal surface and then incubating the gel in a growth medium. A repeatedly renewed minimal essential medium (MEM) is used for about 3 weeks for cell multiplication, followed by a medium containing .beta.-glycerophosphate and ascorbic acid for another 1-2 weeks. The cells may originate from the patient's own bone fragments. The gel (e.g. 0.5% gelatin) is used to hold the cells to the substrate surface.
DE-A-3810803 discloses a method of producing living bone substitute materials by in vitro culturing autologous bone cells from human bone fragments in a repeatedly renewed culture medium, followed by deposition of the cultured cells in a porous calcium phosphate matrix and additional culturing. The composite material can be reimplanted.
WO 94/04657 discloses a bioactive porous glass which is pretreated in such a way that it cannot raise the pH of a tissue medium contacted with the glass. It also reports the seeding of the pretreated porous glass with osteoblasts.
These prior art methods of in vitro production of bone tissue for implanting purposes have not yet been put into practice, probably because fixation of the resulting implant in the body and thus functioning of the implant are insufficient due to limitations in the applying techniques. No biological effect of using a particular culture method was described in the prior art. Furthermore, these prior methods necessitate the introduction of a bone defect (a lesion) in the patient in order to obtain the required bone cells.