Preparation and characterization of laser microporous acellular osteochondral scaffolds / 中国组织工程研究

BACKGROUND: Preparing a scaffold with cartilage derived components and good initial mechanical strength is the direction of tissue engineering cartilage research. OBJECTIVE: To prepare porous acellular osteochondral scaffolds, and to explore their mechanical properties and cell compatibility. METHODS: Osteochondral bone from the porcine knee joint was taken, and then porous osteochondral scaffolds were made by laser microporation technology. Subsequently, the scaffolds were decellularized chemical methods. Scaffold structure was observed by scanning electron microscopy, and the compression modulus of the scaffolds was determined. Bone marrow mesenchymal stem cells were cultured in L-DMEM containing 10% fetal bovine serum (control group) and cultured in the medium extract of porous acellular osteochondral scaffolds (experimental group), respectively. Cell proliferation was detected by cell counting kit-8 method within 5 days of culture. Bone marrow mesenchymal stem cells were seeded on the porous acellular osteochondral scaffolds, and within 28 days of co-culture, cell growth was observed by hematoxylin-eosin staining and toluidine blue staining. RESULTS AND CONCLUSION: (1) Observation under scanning electron microscopy: The porous acellular osteochondral scaffolds had the smooth surface with evenly distributed pores. The pores of the scaffold extended longitudinally into the subchondral bone. (2) Mechanical properties: The average compressive modulus of porous acellular osteochondral scaffolds was 0.77 MPa, which was close to the compression modulus of the normal cartilage (1.15 MPa). (3) Cell counting kit-8 test: There were no differences in cell proliferation between the control and experimental groups at 1, 2, 3, 4 and 5 days of culture. (4) Cell-scaffold co-culture: A large amount of bone marrow mesenchymal stem cells were observed to be adherent to the scaffold after 1 day of culture through hematoxylin-eosin and toluidine blue staining. However, as time went on, a few cells adhered to the pore wall or grew into the pores at 7 and 21 days of culture. There were also some adherent cells but a large amount of cell masses formed in the pores at 28 days of culture. To conclude, the porous acellular osteochondral scaffold has good mechanical properties and cell compatibility.

Intra-articular migration of transplanted bone marrow mesenchymal stem cells in rats with articular cartilage injury / 中国组织工程研究

BACKGROUND: The application of mesenchymal stem cells (MSCs) in the treatment of cartilage damage has become a hot spot of research. Further studies on the distribution of MSCs in the body after injection and on the underlying mechanism of action are needed. OBJECTIVE: To observe the migration of bone marrow mesenchymal stem cells (BMSCs) after injection into the region of osteochondral defect. METHODS: Thirty Sprague-Dawley rats were randomized into two groups (n=15 per group). In the control group, the femoral tochlear was exposed but an osteochondral defect was not made; and after the suture, PKH26-labeled BMSCs were directly injected into the articular cavity of rats. In the experimental group, a cartilage defect of 1 mm in diameter and 1 mm in depth was made in the rat femoral trochlea, and 5×106PKH26-labeled BMSCs were injected into the defect after operation. At 1, 3 and 7 days after injection, the femoral condyle was taken to make frozen sections followed by DAPI staining. The distribution of BMSCs was observed under laser scanning confocal microscope. RESULTS AND CONCLUSION: In the control group, PKH26-labeled BMSCs were not transferred to the subchondral bone. In the experimental group, BMSCs were detected in the subchondral bone area at 1, 3 days after injection of PKH26-BMSCs in the bone cartilage defect area, and the BMSCs were also found in the bone marrow cavity at 7 days after injection. In conclusion, BMSCs in the articular cavity cannot migrate into the subchondral bone and bone marrow cavity unless the cartilage of the femoral condyle is damaged.

Value of Adjuvant Radiotherapy for Thymoma with Myasthenia Gravis after Extended Thymectomy / 中华医学杂志(英文版)

<p><b>Background</b>The co-existence of myasthenia gravis (MG) and thymoma makes the surgical treatment more complicated and adjuvant radiation more controversial. The aim of this study was to investigate adjuvant radiotherapy for thymoma with MG after extended thymectomy.</p><p><b>Methods</b>A total of 181 patients with both MG and thymoma were recruited between 2003 and 2014 at Tongren Hospital, China. Among all the patients, 157 patients received radiation therapy after surgery (Group A); whereas the other 24 patients did not receive radiation therapy (Group B). According to the time that patients started mediastinal radiation therapy, we subdivided the 157 patients in Group A into subgroups (1-month subgroup, n = 98; 2-month subgroup, n = 7; and 3-month subgroup, n = 52). We then compared the effect of the mediastinal radiation therapy across these different groups using the survival rate, the rate of postoperative myasthenic crisis, and the complete stable remission (CSR) rate as the primary endpoints.</p><p><b>Results</b>There was a significant difference in the occurrence of postoperative myasthenic crisis between 1-month subgroup and Group B (χ = 4.631, P = 0.031). The rates of reaching CSR were 32.6% in 1-month subgroup, 25% in 3-month subgroup, and 22.7% in Group B, respectively. The overall survival rates of 1-month subgroup, 3-month subgroup, and Group B were 88.8%, 83.3%, and 77.3%, respectively. Analysis on the Kaplan-Meier survival curves demonstrated that within 8 years after surgery, there was no significant difference in aspects of overall survival and disease-free survival between 1-month subgroup and Group B, and between 3-month subgroup and Group B; over 8 years after surgery, the disease-free survival rates in 1-month subgroup, 3-month subgroup and Group B were 79.4%, 70.6%, and 55.3%, respectively.</p><p><b>Conclusions</b>Adjuvant radiation within 1 month after extended thymectomy may be helpful in controlling postoperative MG, such as decreasing the possibility of postoperative myasthenic crisis, and raising cumulative probabilities of reaching CSR.</p>

Somatosensory disinhibition in patients with paroxysmal kinesigenic dyskinesia / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Paroxysmal kinesigenic dyskinesia (PKD) is characterized by recurrent brief episodes of chorea and dystonia induced by sudden movement. Whether the central nervous system is hyper- or hypoexcitable in PKD remains undetermined. The aim of our study was to compare the somatosensory evoked potential (SEP) recovery cycle, a marker of somatosensory system excitability, in PKD patients and controls.</p><p><b>METHODS</b>Twenty-four PKD patients (mean age of (20.0±5.3) years; 21 males, 3 females) and 18 control age-matched subjects (mean age of (22.0±5.0) years; 17 males, 1 female) were studied. The stimuli were delivered to the median nerve in the affected dominant arm in patients and in the dominant arm in controls. The change in SEP amplitude was measured after paired electrical stimulation at interstimulus intervals (ISIs) of 5, 20, and 40 ms. The SEPs evoked by S2 (test stimulus) were calculated by subtracting the response to S1 (the conditioning stimulus) from the response to a pair of stimuli (S1+S2), and their amplitudes were compared with those of the control response (S1) at each ISI. Analysis of variance (ANOVA) or equivalent was used for non-parametric data.</p><p><b>RESULTS</b>In patients, the P27 amplitude after the single stimulus (S1) was significantly larger than that after the control stimulus. The (S2/S1)×100 ratio for P14 and N30 SEPs did not differ significantly between PKD patients and normal subjects at ISI of 5 ms but were significantly higher in patients at ISIs of 20 and 40 ms (P<0.05).</p><p><b>CONCLUSIONS</b>Somatosensory system disinhibition takes place in PKD. The finding of reduced suppression of different SEPs, each thought to have a different origin, suggests an abnormality of intracortical and subcortical inhibitory circuits.</p>