Soft tissue reconstruction is often needed after massive traumatic damage or cancer removal. In this study, we developed a novel hybrid hydrogel system consisting of alginate particles and a fibrin matrix that could maintain tissue volume long term. Alginate particles were fabricated by mixing 5% alginate with a 20 mM calcium solution. Cells and these alginate particles were then embedded in fibrin (alginate-fibrin) hydrogels using a dual syringe mixer. Cell-hydrogel constructs were evaluated in terms of cell survival and proliferation in the constructs in vitro. The results indicated that cellular viability, spreading and proliferation in the alginate-fibrin hydrogels were significantly higher compared to constructs fabricated with fibrin or alginate only. In vivo explants showed that cells contained within fibrin-only hydrogels did not contribute to neo-tissue formation, and the fibrin was fully degraded within a 12 week period. In the alginate-fibrin system, higher cellularity and vascular ingrowth were observed in vivo. This resulted in neo-tissue formation in the alginate-fibrin hydrogels. These results demonstrate that fibrin may enhance cell proliferation and accelerate the formation of extracellular matrix proteins in the alginate-fibrin system, while the alginate particles could contribute to volume retention. This injectable hybrid system composed of degradable and non-degradable hydrogels may be a preferable approach to the repair of soft tissue defects.

AIm:This study aimed to analyze the effect of rat bone marrow-mesenchymal stem cells (rBM-MSCs) delivery on lesion site after spinal cord injury, and to observe the functional recovery after transplantation. mAterIAl and methOds: MSCs were isolated from rat femurs and tibias. The experimental rat population was divided into four groups: only laminectomy (1); laminectomy+trauma (2); laminectomy+trauma+PBS (3); laminectomy+trauma+MSCs (4). Their motility were scored regularly. After 4-weeks, rats were sacrificed, and their spinal cords were examined for GFP labeled rBM-MSCs by immunostainings. results:In the early posttraumatic period, the ultrastructures of spinal cord tissue were preserved in Group 4. The majority of cells forming the ependymal region around the central canal were found to be MSCs. The gray-and-white-matter around the ependymal region were composed of Nestin+/GFAP+ cells, with astrocytic-like appearance. The scores showed significant motor recovery in Group 4, especially in hind limb functions. However, no obvious change was observed in other groups. COnClusIOn:The increase Nestin+/GFAP+ cells in the gray-and-white-matter around the ependymal region could indicate the potential to self-renew and plasticity. Thus, transplantation of rBM-MSCs might be an effective strategy to improve functional recovery following spinal cord trauma. In conclusion, molecular factors in cell fate decisions could be manipulated to enhance reparative potential of cell-based therapy. KeywOrds: Bone marrow, Mesenchymal stem cells, Spinal cord injury, Functional recovery, Rats ÖZAmAÇ: Bu çalışmada omurilik hasarı sonrası sıçan kemik iliği-mezenkimal kök hücrelerinin (sKİ-MKH) lezyon yerindeki etkisini analiz etmek ve transplantasyon sonrası işlevsel iyileşmeyi gözlemlemek amaçlandı. yÖntem ve GereÇler: MKH'ler sıçan femur ve tibialarından izole edildi. Deney sıçanları dört gruba ayrıldı: sadece laminektomi (1), laminektomi+ travma (2); laminektomi + travma + PBS (3); laminektomi + travma + MKH'ler (4). Sıçanların hareketleri düzenli olarak skorlandı. Dört hafta sonra sıçanlar sakrifiye edildi, omurilikleri immün boyamayla GFP işaretli sKİ-MKH'lerle incelendi.BulGulAr: Erken posttravmatik dönemde, Grup 4'teki omurilik dokusu ultrastrüktürel olarak korundu. Santral kanalın etrafındaki ependimal bölgeyi oluşturan hücrelerinin çoğu MKH'ler olarak saptandı. Ependimal bölgenin etrafındaki gri ve ak maddeler astrositik görünümlü Nestin+/ GFAP+ hücrelerden oluşmuştu. Grup 4'te özellikle arka bacak fonksiyonlarında motor iyileşme belirgindi. Buna karşın, diğer gruplarda belirgin değişiklik izlenmedi.sOnuÇ: Ependimal bölgenin etrafındaki gri ve ak maddede Nestin+/GFAP+ hücrelerin artışı kendini yenileme ve plastisite potansiyellerini gösterebilir ve sKİ-MKH'lerin transplantasyonu spinal kord travması sonrası fonksiyonel iyileşmede etkili bir strateji olabilir. Sonuç olarak, moleküler faktörler hücre kaderini belirleyen hücre tabanlı tedavinin onarıcı potansiyelini artırmak için uygulanabilir.

Genetic defects of GNAS, the imprinted gene encoding the stimulatory G protein αsubunit, are responsible for multiple diseases. Abnormal GNAS imprinting causes pseudohypoparathyroidism type 1B (PHP1B), a prototype of mammalian end-organ hormone resistance. Hypomethylation at the maternally methylated GNAS A/B region is the only shared defect in PHP1B patients. In autosomal dominant (AD) PHP1B kindreds, A/B hypomethylation is associated with maternal microdeletions at either the GNAS NESP55 differentially methylated region or the STX16 gene located ~170 kb upstream. Functional evidence is meager regarding the causality of these microdeletions. Moreover, the mechanisms linking A/B methylation and these putative imprinting control regions (ICRs), NESP-ICR and STX16-ICR, remain unknown. Here, we generated a human embryonic stem cell model of AD-PHP1B by introducing ICR deletions using CRISPR/Cas9. Using this model, we showed that NESP-ICR is required for methylation and transcriptional silencing of A/B on the maternal allele. We also found that SXT16-ICR is a longrange enhancer of NESP55 transcription, which originates from maternal NESP-ICR. Furthermore, we demonstrated that STX16-ICR is an embryonic stage-specific enhancer enabled by the direct binding of pluripotency factors. Our findings uncover an essential GNAS imprinting control mechanism and advance the molecular understanding of the PHP1B pathogenesis.

Titanium (Ti) and its alloys have been frequently used in dental and orthopedic implants, but the undesired oxide layer easily formed on the surface tends to be the cause of implant failure for Ti-based implants. To address this problem, we herein prepared a phosphorylated Ti coating (TiP-Ti) with a micro/nano hierarchically structured topography on commercially pure Ti implants by a hydrothermal method to improve its osteointegration capacity. The surface morphology, chemical composition, and biological activity were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), contact-angle measurement, and protein adsorption assay. Osteointegration of TiP-Ti implants in rat tibia was investigated by biomechanical testing, micro-CT and histological analyses. We further explored the proposed mechanism which improves osteointegration of TiP-Ti implants by proliferation, adhesion, and differentiation assays of rat bone marrow mesenchymal stem cells (BMSCs). Our results demonstrated that the improved osteointegration mainly benefited from the better spread and adhesion of BMSCs on the micro/nano hierarchically structured TiP-Ti surfaces compared to hydroxyapatite coated Ti (HA-Ti), the positive control, and untreated Ti (untreated-Ti), the negative control. In conclusion, TiP-Ti surface is a promising candidate implant surface design to accelerate the osteointegration of Ti-based implants in biomedical applications.

Uncontrolled diabetes is associated with increased risk of bony fractures. However, the mechanisms have yet to be understood. Using high-resolution synchrotron micro-CT, we calculated the changes in the microstructure of femoral cortices of streptozotocin-induced hyperglycemic (STZ) Wistar Albino rats and tested the mechanical properties of the mineralized matrix by nanoindentation. Total lacunar volume of femoral cortices increased in STZ group due to a 9% increase in lacunar density. However, total vascular canal volume decreased in STZ group due to a remarkable decrease in vascular canal diameter (7 ± 0.3 vs. 8.5 ± 0.4 µm). Osteocytic territorial matrix volume was less in the STZ group (14,908 ± 689 µm3) compared with healthy controls (16,367 ± 391 µm3). In conclusion, hyperglycemia increased cellularity and lacunar density, decreased osteocyte territorial matrix, and reduced vascular girth, in addition to decreasing matrix mechanical properties in the STZ group when compared with euglycemic controls.