BackgroundDrugs that can induce mesenchymal stem cell (MSC) mobilization from synovium into synovial uid will enable regenerative medicine in joints without use of exogenous MSCs. An in vitro synovial MSC migration model had previously been developed for screening but had problems in practical application. We herein developed a novel in vitro model, explored cytokines for synovial MSC mobilization with this model, and veri ed whether MSCs in synovial uid increase following intra-articular injection of the cytokine. MethodsHuman synovial MSCs embedded in a mixture of Matrigel and type 1 collagen hydrogel were placed on a culture insert and then put in medium containing migration factor. Of the six cytokines, we identi ed the one that mobilizes the highest number of MSCs. PDGF-BB or PBS was injected into rat knees, and 48 h later, synovial uid was collected and cultured. The cells were examined for MSC properties. ResultsPDGF-BB was the most effective for synovial MSC mobilization among six cytokines. The effect of PDGF-BB was inhibited by a PRGFR inhibitor. Injection of PDGF-BB into rat knees increased colonyforming cells in the synovial uid. These cells had surface epitopes and multipotency comparable to MSCs and a higher capacity for proliferation, colony formation, and chondrogenesis. ConclusionsThis novel in vitro model recapitulated the migration of MSCs from synovium into synovial uid. Our exploration of cytokines revealed that PDGF-BB strongly induced in vitro synovial MSC migration, while intra-articular injection of PDGF-BB increased in vivo MSC numbers in synovial uid in rats.

Angiolipomas are relatively rare benign tumors. Spinal angiolipomas that generally induce slow progressive cord compression are most commonly found in the thoracic region. A 49-year-old female with obesity presented with a 1-week history of progressively worsening back pain, paresthesia of lower limbs, and gait disturbance. When thoracic magnetic resonance imaging (MRI) revealed a dorsal epidural mass at the Th5–Th8 level, the patient underwent a laminectomy for gross total excision of the lesion. Both mature fatty tissue and abnormal proliferating vascular elements with thin or expanded walls were observed in the resected tumor. Nonfiltrating spinal angiolipoma was diagnosed and confirmed by pathology. After the operation, sensory loss, numbness, and gait disturbance were improved following the disappearing severe back pain. Following examinations indicated the absence of recurrence within 1 year. The angiolipomas of the spine are rare causes of spinal cord compression that generally induce slow progressive cord compression, but sudden onset or rapid worsening of neurological deterioration is observed in hemorrhagic spinal angiolipoma.

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Intra-articular injections of mesenchymal stem cells (MSCs) can inhibit the progression of osteoarthritis (OA). Previous reports have used cultured MSCs, but the ability to use thawed cryopreserved MSC stocks would be highly advantageous. Our purpose was to elucidate whether thawed cryopreserved MSCs show comparable inhibitory effects on OA progression in rats to those obtained with cultured MSCs. Cultured rat synovial MSCs or thawed MSCs were compared for in vitro viability and properties. The inhibitory effect of thawed MSCs on OA progression was evaluated by injecting cryopreservation fluid and thawed MSCs in meniscectomized rats. Cartilage degeneration was assessed using gross finding and histological scores. Cultured MSCs were then injected into one knee and thawed MSCs into the contralateral knee of the same individual to compare their effects. Cultured MSCs and MSCs thawed after cryopreservation had comparable in vitro colony formation and chondrogenic potentials. In the rat OA model, the gross finding and histological scores were significantly lower in the thawed MSC group than in the cryopreservation fluid group at 8 weeks. Finally, cartilage degeneration did not differ significantly after injection of cultured and thawed MSCs. In conclusion, thawed MSCs showed comparable inhibitory effects on OA progression to cultured MSCs.

Background Intra-articular injections of mesenchymal stem cells (MSCs) can inhibit the progression of osteoarthritis (OA) in animal studies. Previous reports have used cultured MSCs, but the ability to use thawed cryopreserved MSC stocks would be highly advantageous. Our purpose was to elucidate whether thawed cryopreserved MSCs show comparable inhibitory effects on OA progression in rats to those obtained with cultured MSCs. Methods Cultured rat synovial MSCs or thawed MSCs were compared for in vitro viability and properties. The activity of synovial MSCs derived from rats expressing luciferase was compared by the luminescence intensity both in vitro and in vivo. The inhibitory effect of cultured MSCs on OA progression was evaluated by injecting PBS and cultured MSCs into the right and left knees, respectively, of the same individual meniscectomized rats. A similar test evaluated cryopreservation fluid (95% FBS with 5% DMSO; termed the 95% FBS group) versus thawed MSCs. Cartilage degeneration was assessed at 4 and 8 weeks using gross finding and histological scores. The results were used to set the primary outcome and sample size. Cultured MSCs were then injected into one knee and thawed MSCs into the contralateral knee of the same individual to compare their effects.Results Cultured MSCs and MSCs thawed after cryopreservation in 95% FBS with 5% DMSO had comparable in vitro viability, colony formation, and chondrogenic potential. The luminescence intensity was comparable between the two MSC preparations. In the rat OA model, the gross findings and histological scores for tibial cartilage did not differ at four weeks but were significantly lower in the cultured MSC group than in the PBS group and significantly lower in the thawed MSC group than in the 95% FBS group at eight weeks. These results established the tibial cartilage histological score at eight weeks as the primary outcome and a sample size of nine for comparing cultured versus thawed MSCs. The tibial cartilage histological scores did not differ significantly at eight weeks after injection of cultured and thawed MSCs into the opposite knees of the same individuals.ConclusionsThawed MSCs showed comparable inhibitory effects on OA progression to cultured MSCs.

Background Synovial mesenchymal stem cell (MSC) transplantation improved clinical outcomes in knees with cartilage defects and after repairs of degenerative torn menisci. For these, nucleated cells were cultured with 10% autologous serum for 14 days. Importantly, nucleated cell number and serum volume practically varied by patient, and initial cell density and dish number affected yield/donor. Our purpose was to examine the effect of plating density within range in clinical studies on fold increase and to estimate the MSC yield/donor, which are affected by the nucleated cell number and serum volume.Methods We obtained the data of the autologous serum volume, nucleated cell number, and initial plating cell density from 10 patients who participated in our previous clinical studies. Experimentally, synovial nucleated cells harvested from three patients with osteoarthritis during total knee arthroplasty were cultured with 10% mixed allogenic human serum for 14 days to examine the effect of initial cell density on fold increase. We used both our previous clinical data and our current experimental data to predict the yields of synovial MSCs in nine cases within the range of clinical studies.Results In the clinical studies, collected serum ranged between 87 and 186 ml, harvested nucleated cells ranged between 6.2 and 23 million, and the top five total MSC yields were obtained from donors when the initial plating cell density ranged from 919 to 1905 cells/cm2. Experimentally, fold increase significantly decreased between 700 and 1,900 cells/cm2. In cases where the cell number was low and the serum volume was high, the estimated yield/donor decreased along with the initial density, while in cases where the cell number was high and the serum volume was low, the estimated yield/donor increased along with the initial density. In cases both where some nucleated cells were discarded at low density and no cells were discarded at high density, the maximum yield/donor were obtained when the initial density was the lowest density that does not discard cells.Conclusions There was an optimal initial density that yields the highest number of primary MSCs in a clinical setting when cell numbers and human serum volumes are limited.

Background Drugs that can induce mesenchymal stem cell (MSC) mobilization from synovium into synovial fluid will enable regenerative medicine in joints without use of exogenous MSCs. An in vitro synovial MSC migration model had previously been developed for screening but had problems in practical application. We herein developed a novel in vitro model, explored cytokines for synovial MSC mobilization with this model, and verified whether MSCs in synovial fluid increase following intra-articular injection of the cytokine. Methods Human synovial MSCs embedded in a mixture of Matrigel and type 1 collagen hydrogel were placed on a culture insert and then put in medium containing migration factor. Of the six cytokines, we identified the one that mobilizes the highest number of MSCs. PDGF-BB or PBS was injected into rat knees, and 48 h later, synovial fluid was collected and cultured. The cells were examined for MSC properties. Results PDGF-BB was the most effective for synovial MSC mobilization among six cytokines. The effect of PDGF-BB was inhibited by a PRGFR inhibitor. Injection of PDGF-BB into rat knees increased colony-forming cells in the synovial fluid. These cells had surface epitopes and multipotency comparable to MSCs and a higher capacity for proliferation, colony formation, and chondrogenesis. Conclusions This novel in vitro model recapitulated the migration of MSCs from synovium into synovial fluid. Our exploration of cytokines revealed that PDGF-BB strongly induced in vitro synovial MSC migration, while intra-articular injection of PDGF-BB increased in vivo MSC numbers in synovial fluid in rats.

Background Synovial mesenchymal stem cell (MSC) transplantation improved clinical outcomes in knees with cartilage defects and after repairs of degenerative torn menisci. For these, nucleated cells were cultured with 10% autologous serum for 14 days. Importantly, nucleated cell number and serum volume practically varied by patient, and initial cell density and dish number affected yield/donor. Our purpose was to examine the effect of plating density within range in clinical studies on fold increase and to estimate the MSC yield/donor, which are affected by the nucleated cell number and serum volume. Methods We obtained the data of the autologous serum volume, nucleated cell number, and initial plating cell density from 10 patients who participated in our previous clinical studies. Experimentally, synovial nucleated cells harvested from three patients with osteoarthritis during total knee arthroplasty were cultured with 10% mixed allogenic human serum for 14 days to examine the effect of initial cell density on fold increase. We used both our previous clinical data and our current experimental data to predict the yields of synovial MSCs in nine cases within the range of clinical studies. Results In the clinical studies, collected serum ranged between 87 and 186 ml, harvested nucleated cells ranged between 6.2 and 23 million, and the top five total MSC yields were obtained from donors when the initial plating cell density ranged from 919 to 1905 cells/cm 2 . Experimentally, fold increase significantly decreased between 700 and 1,900 cells/cm 2 . In cases where the cell number was low and the serum volume was high, the estimated yield/donor decreased along with the initial density, while in cases where the cell number was high and the serum volume was low, the estimated yield/donor increased along with the initial density. In cases both where some nucleated cells were discarded at low density and no cells were discarded at high density, the maximum yield/donor were obtained when the initial density was the lowest density that does not discard cells. Conclusions There was an optimal initial density that yields the highest number of primary MSCs in a clinical setting when cell numbers and human serum volumes are limited.