جستجوی مقالات مرتبط با کلیدواژه « hydroxyapatite » در نشریات گروه « دامپزشکی »

Mesenchymal stem cells (BMSC) can differentiate into the mesodermal lineage. The use of nanocomposite mesenchymal stem cells in the repair of the bone defect of the rat femur. In this study, 36 male Wistar rats were randomly divided into three groups on days 15, 30, and 45. The studied groups include Sham; the defect was left without scaffolding, and the area was closed. HA: The defect was first filled and then closed using hydroxyapatite. Autograft: The defect was filled using pieces of bone from the drilled area and the stem cells (MSCs); that was the same as the control group, but the injection of mesenchymal stem cells was done locally at the time of surgery. In this way, a 5 cm long incision was made in aseptic conditions along the right hind limb on the medial diaphysis of the femur. The periosteum was separated from the diaphysis by a periosteal lifter. A defect with a diameter of 2 mm was created in the femur. Bone samples were fixed, decalcified, and processed for histopathological evaluation on days 30 and 45 to grade lesions and repair rate. The restorative effects of using stem cells were significantly different in all cases compared to other groups. It can be acknowledged that the presence of mesenchymal stem cells positively affects the healing process and shows satisfactory bone strength. Mesenchymal stem cells can be widely used in orthopedic surgery and tissue engineering.

Fracture repair involves proliferation and differentiation of multiple tissue types in a sequence followed by regeneration. All of these processes may be affected by medications. Some drugs can affect the proliferation of primary callus tissue, others can affect the differentiation of chondrocytes or osteoblasts, formation of capillaries, sensitivity to mechanical input, etc. Therefore, the subject of drugs and fracture repair not only includes pharmacology and orthopedics, but also includes a wide scope. Repair steps after bone damage include: stage 1: (swelling stage), stage 2: (primary bone repair): over the next 4 to 21 days, a callus is formed around the broken bone. In this stage, a substance called collagen gradually replaces the blood clot. Step 3: (secondary bone repair) approximately two weeks after the fracture, cells called osteoblasts start working. These cells cause new bone to fuse and provide minerals needed for bone strength. Step 4: (reconstruction step): in this stage, cells called osteoclasts make the needed changes and adjustments. These cells break down any extra bone that is formed during this healing phase to return the bone shape to its normal status. In current veterinary and also human orthopedics, bone grafts are used for stimulation of fractures healing, accelerate joint fusion and repair of bone defects. Native grafted bone in addition to healing stimulator substances, contains cells that do not stimulate immune reactions and do not transmit infectious diseases. Currently, due to the problems of autologous bone grafting, the desire to use non-autologous bone grafts such as allograft and xenograft has increased. Kinetic hydroxyapatite, tricalcium phosphate and their both combination are among the common materials for bone grafting. Hydroxyapatite works as a scaffold for the growth of bone-forming cells; tarantula cubensis is an extract that is widely used in the treatment of tumors, smallpox, septicemia and toxemic diseases. Also, other materials that are used as substitutes, after being implanted at the site of bone lesions, induce the differentiation of undifferentiated mesenchymal cells present at the site of the lesion into chondrocytes or immature bone cells, and finally, the defects are successfully repaired.

This study was conducted with the aim of investigating the effectiveness of titanium dioxide nanocomposite scaffolds for the reconstruction of femur defects in rabbits. To investigate the effect of nanocomposites on the healing processes of broken bone (bone defect). 18 New Zealand adult male white rabbits weighing 3 kg were studied. A cylindrical defect with a diameter of 6 x 5 mm was created in the femur of rabbits. The animals were divided into three experimental groups. The experimental groups after the defect were created included control, control (hydroxyapatite) and treatment (titanium dioxide). On the 15th and 45th days after surgery, the animals were killed and a sample was taken from the bone defect site and placed in 10% buffered formalin. 5 μm sections were evaluated after general and trichrome staining. Improvement of inflammation on day 15 and formation of new bone on day 45 in the nanocomposite group was the best in terms of ossification repair unit and reduction of inflammation. Nanocomposite had a significant recovery function in bone regeneration of defective areas.

The loss of bone fragments, often due to trauma, infection, mass loss, or even complete bone regeneration after complicated fractures, is one of the constant challenges in medicine and veterinary medicine. Over the last decades, many efforts have been made to obtain materials that have the potential for high bone regeneration and to replace alternatives to autograft or zenografts. In this study, 45 adult male New Zealand male rabbits weighing 3-5 mg​​/kg, randomly divided into 3 groups of 15, were used. During surgery on the femur of each rabbit, a bilateral, 6 mm diameter defect was created. In the first group (control), no substance was used, in the second group, hydroxyapatite, and in the third group, nanocomposite tri-calcium phosphate (TCP) was used to fill the defect. Bone specimens were harvested for histopathologic evaluation on days 15, 30 and 45 and for evaluation of 4 indexes of union, spongiosa, cortex and bone marrow. The results showed that the results of using nanocomposite tricalcium phosphate in comparison with other groups were significantly different in all cases. Therefore, according to the results, it can be admitted that nanocomposite tri-calcium phosphate scaffold has a positive effect on the healing process and has good bone strength, so it can be widely used in orthopedic surgery as well as tissue engineering.