ABSTRACT
Objective To investigate the difference of matrix stiffness in different regions of tibial plateau in osteoarthritis (OA) and its effects on morphology of the cartilage and mitochondria. Methods The tibial plateau cartilage specimens of OA were obtained for nanoindentation test, transmission electron microscopy and histological analysis. The stiffness of cartilage matrix in different regions of OA tibial plateau was detected by nano-indentation. The morphology of cartilage mitochondria in different regions was observed by transmission electron microscopy, and the changes of mitochondrial plane area, shape and ridge volume density were quantitatively analyzed. Cartilage injury in different regions of OA tibial plateau was observed by histological staining. Results The cartilage of OA tibial plateau showed regional heterogeneity, and the cartilage and mitochondria on medial side of varus knee OA were more severe, and the matrix stiffness was higher. The OA scores were positively correlated with matrix stiffness. There was also a significant correlation between OA scores and mitochondrial morphology: the higher OA scores, the larger and rounder mitochondrial plane area, and the lower cristae volume density. Conclusions The differences of tibial plateau revealed the correlation between cartilage matrix stiffness, OA scores and mitochondrial morphological parameters. The increased cartilage matrix stiffness may be the main cause of chondrocyte mitochondrial injury, and further aggravate the progression of OA.
ABSTRACT
With the multi-directional differentiation potential such as osteogenic differentiation, chondrogenic differentiation and adipogenic differentiation, mesenchymal stem cells (MSCs) have been widely used in basic research and clinical applications. The differentiation potential of MSCs is altered during senescence. Osteogenic differentiation potential decreases, while the lipogenic differentiation potential increases in aging MSCs. Changes in differentiation potential of MSCs during senescence are accompanied with cell physical heterogeneity variation (cell size, cell stiffness and nucleoplasmic ratio). Studies have shown that changes in physical heterogeneity of stem cells may be a key factor leading to the differences in differentiation potential of MSCs. Therefore, studies on physical heterogeneity variation of MSCs during senescence will provide a new research direction in fate prediction of stem cell. In this review, the effects of physical heterogeneity variation on differentiation potential of MSCs were summarized, and the corresponding mechanism was also discussed.
ABSTRACT
Objective To study the relationship of the tibial plateau subchondral trabecular bone (STB) microstructure and the cartilage degeneration with the lower limb alignment based on individual trabecula segmentation (ITS) and histology analysis in knee osteoarthritis (OA). Methods Hip-knee-ankle (HKA) angles were measured on the full-length lower extremity films of patients before total knee arthroplasty (TKA). The tibial plateau excised from the TKA were collected for micro-CT scanning and ITS analysis. The cartilage degeneration was evaluated by histology. The relationship between the HKA angle and the changes in microstructural parameters of STB and cartilage degeneration were analyzed. ResultsThe plate, rod and axial bone trabecular volume fraction (BV/TV, pBV/TV, pBV/TV), ratio of trabecular plate versus rod (P/R), plate trabecular number density (pTb.N), plate trabecular thickness (pTb.Th), trabecular plate surface area (pTb.S), trabecular rod length (rTb.L), and plate-plate and plate-rod junction density (P-P Junc.D, P-R Junc.D) of the subchondral bone of the tibial plateau were significantly related to the cartilage degeneration OARSI score and the HKA angle. The greater the deviation of the lower limb alignment, the greater the number of subchondral trabeculae, the thicker the trabeculae, the greater the bone mass, the stronger the connectivity, especially the plate trabeculae on the affected side of tibial plateau, and the higher the OARSI score of cartilage degeneration. Conclusions Abnormal lower limb alignment may cause abnormal microstructure of the plate and rod STB of the tibial plateau by changing the stress distribution of the knee, especially the significant increase and thickening of the plate trabecular and axial trabecular bone, which may be an important risk factor that further aggravates the degeneration of articular cartilage and the progress of OA. Therefore, lower limb alignment correction with surgical intervention and improving STB with bone metabolism agents may efficiently contribute to preventing cartilage damage and mitigate OA progression.
ABSTRACT
Bone is a dynamic organ, and the morphology, structure and function of bone can vary with the size, direction and form of mechanical stimulation. Appropriate mechanical stimulation is the key to maintain the dynamic balance of bone formation and bone resorption. However, with aging, the senescence of bone tissues causes a series of changes, including bone microenvironment, osteocyte morphology, signaling pathways in the osteocyte, etc., which weakens its mechanical response ability and then leads to osteoporosis and other diseases. Therefore, it is of great significance to study how aging affects the mechanical response of osteocyte. This review mainly discusses the influence of aging on mechanical response of the osteocyte.
ABSTRACT
Notch signaling pathway has a wide range of effects in the field of embryonic development, nervous system, vascular system, endocrine system and tumor. In recent years, studies have shown that Notch plays an important role in the regulation of bone metabolism, especially in bone remodeling. The disorder of bone remodeling is closely related to the progress of diseases such as osteoporosis and osteoarthritis. Notch signaling pathway can affect the process of bone remodeling by regulating the function of different cells in bone tissues, but its specific participation in different cells is still unknown. This review summarizes recent advances about the role of Notch signaling in bone remodeling.
ABSTRACT
Objective To investigate the structure and biomechanical property differences in different regions of the femoral head for elderly patients with femoral neck fractures,and to study its influence on internal fixation for fracture.Methods Twenty femoral head specimens were collected from elderly patients with femoral neck fracture after joint replacement.The femoral head was divided into 3 parts (lateral,inferior and medial region) with reference to anatomical markers on surface of the femoral head.After the position and drilling direction of the ring drill were determined,a circular drill was used to obtain the cylindrical cancellous bone columns with 10 mm in diameter and 10 mm in height.The data of cancellous bone columns in different regions were analyzed by Micro-CT scanning system,including bone volume fraction (BVF),trabecular space (Tb.Sp),trabecular thickness (Tb.Th),the number of trabecular number (Tb.N),the bone surface volume ratio (bone surface/bone volume,BS/BV),structural model index (SMI).Mechanical property differences of bone tissues in different regions were calculated by micro-finite element analysis.Results Bone mass in the elderly osteoporotic femoral head decreased,and there were significant differences in bone microstructure and mechanical properties in different regions of the femoral head.Bone microstructure and mechanical properties in medial region were obviously superior to those in lateral and interior region.Conclusions The bone structure and mechanical strength in medial region of the femoral head are obvious superior to those in lateral and inferior regions.The position for internal fixation should be fully considered during treatment of osteoporotic femoral neck fracture in clinic.
ABSTRACT
@#Objective To study the relationship between knee osteoarthritis progression and the ration of fat,lean,or bone mineral content(BMC).Methods 36 joints of knee with osteoarthritis in 31 women were divided into two groups according to the knee joint space,joint space narrowing group and non-narrowing group.The body mass index(BMI)was calculated.The X-ray(weight bearing)of knee joint was taken.The fat,lean,BMC and mass of leg were detected with the dual energy X-ray absorptiometry(DXA).Results There was no distinct difference between sides and age distribution for the tested groups(P>0.05).The BMI and fat/mass ratio of leg in the joint space narrowing group were obviously higher than that of the non-narrowing group(P<0.05),while the lean/mass ratio of leg in the joint space narrowing group was distinctly lower than that of the non-narrowing group(P<0.05).Conclusion The deterioration of the female knee osteoarthritis can be mainly attributed to the increase of the BMI and fat/mass ratio as well as the decrease of the lean/mass ratio of leg.