Sirong Shi

The fabrication of biomimetic biphasic CAN-PAC hydrogel with a seamless interfacial layer applied in osteochondral defect repair

Cartilage tissue engineering based on biomimetic scaffolds has become a rapidly developing strategy for repairing cartilage defects. In this study, a biphasic CAN-PAC hydrogel for osteochondral defect (OCD) regeneration was fabricated based on the density difference between the two layers via a thermally reactive, rapid cross-linking method. The upper hydrogel was cross-linked by CSMA and NIPAm, and the lower hydrogel was composed of PECDA, AAm and PEGDA. The interface between the two layers was first grafted by the physical cross-linking of calcium gluconate and alginate, followed by the chemical cross-linking of the carbon-carbon double bonds in the other components. The pore sizes of the upper and lower hydrogels were ~187.4 and ~112.6 μm, respectively. The moduli of the upper and lower hydrogels were ~0.065 and ~0.261 MPa. This prepared bilayer hydrogel exhibited the characteristics of mimetic composition, mimetic structure and mimetic stiffness, which provided a microenvironment for sustaining cell attachment and viability. Meanwhile, the biodegradability and biocompatibility of the CAN-PAC hydrogel were examined in vivo. Furthermore, an osteochondral defect model was developed in rabbits, and the bilayer hydrogels were implanted into the defect. The regenerated tissues in the bilayer hydrogel group exhibited new translucent cartilage and repaired subchondral bone, indicating that the hydrogel can enhance the repair of osteochondral defects.

Effects of low oxygen tension on gene profile of soluble growth factors in co-cultured adipose-derived stromal cells and chondrocytes

Moving towards development of optimized cartilage regeneration with adipose‐derived stromal cells (ASCs), the focus of this study was on investigating the influence of hypoxia on soluble factors secreted by ASCs and chondrocytes after crosstalk.

Tetrahedral DNA Nanostructure: A Potential Promoter for Cartilage Tissue Regeneration via Regulating Chondrocyte Phenotype and Proliferation.

Utilizing biomaterials to regulate the phenotype and proliferation of chondrocytes is a promising approach for effective cartilage tissue regeneration. Recently, a significant amount of effort has been invested into directing chondrocytes toward a desired location and function by utilizing biomaterials to control the dedifferentiation and phenotypic loss of chondrocytes during in vitro monolayer culture. Here, the transmission signals resulting from tetrahedral DNA nanostructures (TDNs) in the regulation of chondrocyte phenotype and proliferation are exploited. TDNs, new DNA nanomaterials, have been considered as promising materials in biomedical fields. Upon exposure to TDNs, chondrocyte phenotype is significantly enhanced, accompanied by lower gene expression related to Notch signaling pathway and higher expression of type II collagen. In addition, the cell proliferation and morphology of chondrocytes are changed after exposure to TDNs. In conclusion, this work demonstrates that TDNs are potentially useful mechanism in cartilage tissue regeneration from chondrocytes, whereby chondrocyte phenotype and proliferation can be retained.

Self-Assembled Tetrahedral DNA Nanostructures Promote Adipose-Derived Stem Cell Migration via lncRNA XLOC 010623 and RHOA/ROCK2 Signal Pathway

Self-assembled tetrahedral DNA nanostructures (TDNs) with precise sizes have been extensively applied in various fields owing to their exceptional mechanical rigidity, structural stability, and modification versatility. In addition, TDNs can be internalized by mammalian cells and remain mainly intact within the cytoplasm by escaping degradation by nucleases. Here, we studied the effects of TDNs on cell migration and the underlying molecular mechanisms. TDNs remarkably enhanced the migration of rat adipose-derived stem cells and down-regulated the long noncoding RNA (lncRNA) XLOC 010623 to activate the mRNA expression of Tiam1 and Rac1. Furthermore, TDNs highly up-regulated the mRNA and protein expression of RHOA, ROCK2, and VCL. These results indicate that TDNs suppressed the transcription of lncRNA XLOC 010623 and activated the TIAM1/RAC1 and RHOA/ROCK2 signaling pathways to promote cell migration. On the basis of these findings, TDNs show a high potential for application in tissue repair and regenerative medicine as a functional three-dimensional DNA nanomaterial.

The JAK/STAT3 signalling pathway regulated angiogenesis in an endothelial cell/adipose-derived stromal cell co-culture, 3D gel model

The aim of the study was to investigate the role of the JAK/STAT3 signalling pathway in angiogenesis.

Modulation of chondrocyte motility by tetrahedral DNA nanostructures

Contemporarily, a highly increasing attention was paid to nanoconstructs, particularly DNA nanostructures possessing precise organization, functional manipulation, biocompatibility and biodegradability. Amongst these DNA nanomaterials, tetrahedral DNA nanostructures (TDNs) are a significantly ideal bionanomaterials with focusing on the property that can be internalized into cytoplasm in the absence of transfection. Therefore, the focus of this study was on investigating the influence of TDNs on the chondrocytes locomotion.

Aptamer-modified tetrahedral DNA nanostructure for tumor-targeted drug delivery

Tetrahedral DNA nanostructures (TDNs) are considered promising drug delivery carriers because they are able to permeate cellular membrane and are biocompatible and biodegradable. Furthermore, they can be modified by functional groups. To improve the drug-delivering ability of TDNs, we chose anticancer aptamer AS1411 to modify TDNs for tumor-targeted drug delivery. AS1411 can specifically bind to nucleolin, which is overexpressed on the cell membrane of tumor cells. Furthermore, AS1411 can inhibit NF-κB signaling and reduce the expression of bcl-2. In this study, we compared the intracellular localization of AS1411-modified TDNs (Apt-TDNs) with that of TDNs in different cells under hypoxic condition. Furthermore, we compared the effects of Apt-TDNs and TDNs on cell growth and cell cycle under hypoxic condition. A substantial amount of Apt-TDNs entered and accumulated in the nucleus of MCF-7 cells; however, the amount of Apt-TDNs that entered L929 cells was comparatively less. TDNs entered in much lower quantity in MCF-7 cells than Apt-TDNs. Moreover, there was little difference in the amount of TDNs that entered L929 cells and MCF-7 cells. Apt-TDNs can inhibit MCF-7 cell growth and promote L929 cell growth, while TDNs can promote both MCF-7 and L929 cell growth. Thus, the results indicate that Apt-TDNs are more effective tumor-targeted drug delivery vehicles than TDNs, with the ability to specifically inhibit tumor cell growth.

Fabrication of Calcium Phosphate Microflowers and Their Extended Application in Bone Regeneration

The structure of materials is known to play an important role in material function. Nowadays, flowerlike structures have gained attention for studies not only in analytical chemistry, but also in biomaterial design. In this study, flowerlike structures were applied in bone regeneration in the form of calcium phosphate microflowers. The material was synthesized by a simple and environmentally friendly method. We characterized the structure and properties of the microflower using various methods. Cytotoxicity and osteogenesis-related gene regulations of the microflower were investigated in vitro. Cell uptake was observed by immunofluorescence. Rat calvarial critical-size defect models were successfully established to further confirm the enhanced bone regeneration ability of this material. We expect that this novel study will be of practical importance for the extended application of flowerlike materials and will provide new insights into the optimization of the morphology of calcium phosphate materials.

Understanding the Biomedical Effects of the Self-Assembled Tetrahedral DNA Nanostructure on Living Cells

Recently, much attention has been paid to DNA again due to the successful synthesis of DNA-based nanostructures that can enter cells via endocytosis and thus have great potential in biomedical fields. However, the impacts of DNA nanostructures on life activities of a living cell are unknown. Herein, the promotion effect of tetrahedral DNA nanostructure (TDN) on cell growth and the underlying molecular mechanisms are reported. Upon exposure to TDN, cell proliferation is significantly enhanced, accompanied by up-regulation of cyclin-dependent kinase like-1 gene, changes in cell cycle distribution, and up-regulation of the Wnt/β-catenin signaling-related proteins (β-catenin, Lef 1 and cyclin D). In contrast, single-stranded DNA (ssDNA) shows no such functions. Furthermore, TDN is able to reverse the inhibition effect of DKK1, a specific inhibitor for Wnt/β-catenin pathway. Hence, the Wnt/β-catenin pathway is the target for TDN to promote cell proliferation. The findings allow TDN to be a novel functional nanomaterial that has great potential in tissue repair and regeneration medicine.

Notch Signaling Pathway Regulates Angiogenesis via Endothelial Cell in 3D Co‐Culture Model

This study aimed to investigate the role of Notch signaling pathway for angiogenesis in a three‐dimensional (3D) collagen gel model with co‐culture of adipose‐derived stromal cells (ASCs) and endothelial cells (ECs). A 3D collagen gel model was established in vitro by implanting both ASCs from green fluorescent protein‐labeled mouse and ECs from red fluorescent protein‐labeled mouse, and the phenomena of angiogenesis with Notch signaling inducer Jagged1, inhibitor DAPT and PBS, respectively were observed by confocal laser scanning microscopy. Semi‐quantitative PCR and immunofluorescent staining were conducted to detect expressions of angiogenesis‐related genes and proteins. Angiogenesis in the co‐culture gels was promoted by Jagged1 treatment while attenuated by DAPT treatment, compared to control group. In co‐culture system of ASCs and ECs, the gene expressions of VEGFA, VEGFB, Notch1, Notch2, Hes1, Hey1, VEGFR1,and the protein expression of VEGFA, VEGFB, Notch1, Hes1, Hey1 were increased by Jagged1 treatment and decreased by DAPT treatment in ECs. And the result of VEGFR3 was the opposite. However, the same results did not appear completely in ASCs. These results revealed the VEGFA/B‐Notch1/2‐Hes1/Hey1‐ VEGFR1/3 signal axis played an important role in angiogenesis when ASCs and ECs were co‐cultured in a 3D collagen gel model. J. Cell. Physiol. 232: 1548–1558, 2017.