Damaged bones may regenerate from stem cells
UN/DICYT A cellular therapy technique helps in treating bone defects produced by accidents, shootings or bone infections, among others. Its application would avoid, among other alternatives, use of synthetic bone grafts. This is a bone regeneration alternative using mesenchymal stem cells which are capable of producing several types of cells from human support cells such as cartilage, bone and fat.
Although up to now the model only has been used in animals (rabbits), it promises to turn into a technique for treatment of bone defects in large bones.
The proposal of Orthopedist and Traumatologist Gabriel Fletscher Covaleda, and headed by Dr. Orlando Chaparro and Dr. Italy Linero of the Universidad Nacional de Colombia (UNal) Faculty of Medicine was recently bestowed the best scientific poster award at the American Congress of Orthopedics and Traumatology recently held in Orlando (Florida).
“In orthopedics secondary bone loss is common due to bone infections, and other traumatic pathologies such as accidents, shootings, and explosions among others,” said Fletscher.
According to the size of the lost bone, physicians use bone grafts for small lesions. For more complex lesions with significant loss of bone (more than 4 cms) they use corticoid distraction techniques to install external fixing devices which are fixed to the bone using wire or screws which progressively help lengthen the bone of the patient, regenerating bone segments.
Another option is the induced membrane technique (forming a biological membrane in the area of the bone defect in presence of an alien to the body element) described by Dr. Alain Masquelet in 1986. It was initially used in reconstructing defects in long bones, especially the femur and the tibia. Due to the excellent results it has been used in other locations of the bone anatomy.
This technique is carried out in two stages. In the first the affected bone is surgically removed and the remaining space is filled with bone cement which is later extracted (time in which the biological membrane is formed); furthermore the space is filled with bone graft (second stage).
“The procedure has demonstrated that bone grafts integrate better if a membrane is previously formed around the cement. However in case of extensive bone defects, the volume of the bone graft is not sufficient therefore they are currently looking for other alternatives to fill the defect appropriately without losing membrane properties,” said the researcher.
Precisely the research group is trying to induce bone reproduction by using mesenchymal stem cells instead of using a bone graft in the second surgical stage of the Masquelet technique.
“These types of cells, present on both embryonic tissues as in adults have the possibility of turning into different tissues such as bone, cartilage, fat, muscle or inclusively nervous tissue. However its capability to stimulate the surrounding environment secreting different growth factors has also been demonstrated and is the basis for the research developed,” added Fletscher.
Response in rabbits
The research project was carried out on nine rabbits using the Masquelet technique. In all animals they resected a segment of femoral diaphysis with the purpose of regenerating it by using growth factors produced by mesenchymal stem cells.
During the first surgery they performed a stabilization of the bone using an external fixing device and the area of the defect was filled with a cement spacer (polymethylmethacrylate.)
For the second surgery, animals were organized in four groups. In the first they analyzed the paracrine effect (molecule secretion which estimate or help tissue reparation) of mesenchymal stem cells. For the second they analyzed the cellular capacity and the other two were used as control groups.
Later they carried out a radiological assessment and compared the results among the rabbit groups regarding the closure degree of the bone defect.
The most important result was evidence of closure of the bone defect through the paracrine effect produced by mesenchymal stem cells.