Injury to muscles is very common. We have previously observed that basic fibroblast growth factor (b-FGF), insulin growth factor type 1 (IGF-1) and nerve growth factor (NGF) are potent stimulators of the proliferation and fusion of myoblasts in vitro. We therefore injected these growth factors into mice with lacerations of the gastrocnemius muscle. The muscle regeneration was evaluated at one week by histological staining and quantitative histology. Muscle healing was assessed histologically and the contractile properties were measured one month after injury. Our findings showed that b-FGF, IGF and to a less extent NGF enhanced muscle regeneration in vivo compared with control muscle. At one month, muscles treated with IGF-1 and b-FGF showed improved healing and significantly increased fast-twitch and tetanus strengths. Our results suggest that b-FGF and IGF-1 stimulated muscle healing and may have a considerable effect on the treatment of muscle injuries

We hypothesised that meniscal tears treated with mesenchymal stem cells (MSCs) together with a conventional suturing technique would show improved healing compared with those treated by a conventional suturing technique alone. In a controlled laboratory study 28 adult pigs (56 knees) underwent meniscal procedures after the creation of a radial incision to represent a tear. Group 1 (n = 9) had a radial meniscal tear which was left untreated. In group 2 (n = 19) the incision was repaired with sutures and fibrin glue and in group 3, the experimental group (n = 28), treatment was by MSCs, suturing and fibrin glue.

At eight weeks, macroscopic examination of group 1 showed no healing in any specimens. In group 2 no healing was found in 12 specimens and incomplete healing in seven. The experimental group 3 had 21 specimens with complete healing, five with incomplete healing and two with no healing. Between the experimental group and each of the control groups this difference was significant (p < 0.001).

The histological and macroscopic findings showed that the repair of meniscal tears in the avascular zone was significantly improved with MSCs, but that the mechanical properties of the healed menisci remained reduced.

An increasing number of patients are treated by autologous chondrocyte implantation (ACI). This study tests the hypothesis that culture within a defined chondrogenic medium containing TGF-β enhances the reexpression of a chondrocytic phenotype and the subsequent production of cartilaginous extracellular matrix by human chondrocytes used in ACI. Chondrocytes surplus to clinical requirements for ACI from 24 patients were pelleted and cultured in either DMEM (Dulbecco’s modified eagles medium)/ITS+Premix/TGF-β1 or DMEM/10%FCS (fetal calf serum) and were subsequently analysed biochemically and morphologically.

Pellets cultured in DMEM/ITS+/TGF-β1 stained positively for type-II collagen, while those maintained in DMEM/10%FCS expressed type-I collagen. The pellets cultured in DMEM/ITS+/TGF-β1 were larger and contained significantly greater amounts of DNA and glycosaminoglycans. This study suggests that the use of a defined medium containing TGF-β is necessary to induce the re-expression of a differentiated chondrocytic phenotype and the subsequent stimulation of glycosaminoglycan and type-II collagen production by human monolayer expanded chondrocytes.

Implantation of autologous chondrocytes and matrix autologous chondrocytes are techniques of cartilage repair used in the young adult knee which require harvesting of healthy cartilage and which may cause iatrogenic damage to the joint. This study explores alternative sources of autologous cells.

Chondrocytes obtained from autologous bone-marrow-derived cells and those from the damaged cartilage within the lesion itself are shown to be viable alternatives to harvest-derived cells. A sufficient number and quality of cells were obtained by the new techniques and may be suitable for autologous chondrocyte and matrix autologous chondrocyte implantation.

We isolated multilineage mesenchymal progenitor cells from haematomas collected from fracture sites. After the haematoma was manually removed from the fracture site it was cut into strips and cultured. Homogenous fibroblastic adherent cells were obtained. Flow cytometry revealed that the adherent cells were consistently positive for mesenchymal stem-cell-related markers CD29, CD44, CD105 and CD166, and were negative for the haemopoietic markers CD14, CD34, CD45 and CD133 similar to bone-marrow-derived mesenchymal stem cells. In the presence of lineage-specific induction factors the adherent cells could differentiate in vitro into osteogenic, chondrogenic and adipogenic cells.

Our results indicate that haematomas found at a fracture site contain multilineage mesenchymal progenitor cells and play an important role in bone healing. Our findings imply that to enhance healing the haematoma should not be removed from the fracture site during osteosynthesis.