Constructions of ROS-responsive titanium-hydroxyapatite implant for mesenchymal stem cell recruitment in peri-implant space and bone formation in osteoporosis microenvironment

To solve the issue of unsatisfactory recruitment of mesenchymal stem cells(MSCs)around implant in osteoporotic fractures,we fabricated a ROS-responsive system on titanium surface through hydroxyapatite coating and biomolecule grafting.The porous hydroxyapatite and phosphorylated osteogenic growth peptides(p-OGP)were introduced onto titanium surface to synergistically improve osteogenic differentiation of MSCs.After the p-OGPpromoted expression of osteogenic related proteins,the calcium and phosphate ions were released through the degradation of hydroxyapatite and integrated into bone tissues to boost the mineralization of bone matrix.The ROS-triggered release of DNA aptamer(Apt)19S in the osteoporotic microenvironment guides MSC migration to implant site due to its high affinity with alkaline phosphatase on the membrane of MSCs.Once MSCs reached the implant interface,their osteogenic differentiation potential was enhanced by p-OGP and hydroxyapatite to promote bone regeneration.The study here provided a simple and novel strategy to prepare functional titanium implants for osteoporotic bone fracture repair.

Emodin suppresses LPS-induced proinflammatory responses and nuclear factor-B activation by disruption of lipid rafts and TLR-4 recruitment in endothelial cells

Emodin [1,3,8-Trihydroxy-6-methylanthraquinone] has been reported to exhibit vascular anti-inflammatory properties.However,the relevant anti-inflammatory mechanisms are not well understood.The present study was design to explore the molecular target(s) of emodin

Recruitment of endogenous progenitor cells by erythropoietin loaded particles for in situ cartilage regeneration

Cartilage injury affects millions of people throughout the world,and at this time there is no cure.While transplantation of stem cells has shown some success in the treatment of injured cartilage,such treatment is limited by limited cell sources and safety concerns.To overcome these drawbacks,a microscaffolds system was developed capable of targeting,reducing the inflammatory response and recruiting endogenous progenitor cells to cartilage-defect.Erythropoietin(EPO)-loaded-hyaluronic acid(HA)microscaffolds(HA+EPO)were fabricated and characterized.HA-microscaffolds showed good cell-compatibility and could target chondrocytes via CD44 receptors.HA+EPO was designed to slowly release EPO while recruiting progenitor cells.Finally,the ability of HA+EPO to repair cartilage-defects was assessed using a rabbit model of full-thickness cartilagedefect.Our results showed that the intra-articular administration of EPO,HA,and EPO+HA reduced the number of inflammatory cells inside the synovial-fluid,while EPO+HA had the greatest anti-inflammatory effects.Furthermore,among all groups,EPO+HA achieved the greatest progenitor cell recruitment and subsequent chondrogenesis.The results of this work support that,by targeting and localizing the release of growthfactors,HA+EPO can reduce inflammatory responses and promote progenitor cells responses.This new platform represents an alternative treatment to stem-cell transplantation for the treatment of cartilage injury.

Arabidopsis EXO70A1 recruits Patellin3 to the cell membrane independent of its role as an exocyst subunit

The exocyst is a well-known complex which tethers vesicles at the cell membrane before fusion. Whether an individual subunit can execute a unique function is largely unknown. Using yeast-two-hybrid （Y2H） analysis, we found that EXO7oA1 interacted with the GOLD domain of Patellin3 （PATL3）. The direct EXO7OA1-PATL3 interaction was supported by in vitro and in vivo experiments. In Arabidopsis, PATL3-GFP colocalized with EXO7oA1 predominantly at the cell membrane, and PATL3 localization was insensitive to BFA and TryA23. Remarkably, in the exo7oa1 mutant, PATL3 proteins accumulated as punctate structures within the cytosol, which did not colocalize with several endomembrane compartment markers, and was insensitive to BFA. Furthermore, PATL3 localization was not changed in the exo7oe2, PRsec6 or exo84b mutants. These data suggested that EXO7oA1, but not other exocyst subunits, was responsible for PATL3 localization, which is independent of its role in secretory/recycling vesicletethering/fusion. Both EXO7oA1 and PATL3 were shown to bind PI4P and PI（4,5）P2 in vitro. Evidence was obtained that the other four members of the PATL family bound to EXO7oA1 as well, and shared a similar localization pattern as PATL3. These findings offered new insights into exocyst subunitspecific function, and provided data and tools for further characterization of PATL family proteins.

Advanced bioactive glue tethering Lubricin/PRG4 to promote integrated healing of avascular meniscus tears

Meniscus injuries are extremely common with approximately one million patients undergoing surgical treatment annually in the U.S. alone, but no regenerative therapy exist. Previously, we showed that controlled applications of connective tissue growth factor (CTGF) and transforming growth factor beta 3 (TGFβ3) via fibrin-based bio-glue facilitate meniscus healing by inducing recruitment and stepwise differentiation of synovial mesenchymal stem/progenitor cells. Here, we first explored the potential of genipin, a natural crosslinker, to enhance fibrin-based glue’s mechanical and degradation properties. In parallel, we identified the harmful effects of lubricin on meniscus healing and investigated the mechanism of lubricin deposition on the injured meniscus surface. We found that the pre-deposition of hyaluronic acid (HA) on the torn meniscus surface mediates lubricin deposition. Then we implemented chemical modifications with heparin conjugation and CD44 on our bioactive glue to achieve strong initial bonding and integration of lubricin pre-coated meniscal tissues. Our data suggested that heparin conjugation significantly enhances lubricin-coated meniscal tissues. Similarly, CD44, exhibiting a strong binding affinity to lubricin and hyaluronic acid (HA), further improved the integrated healing of HA/lubricin pre-coated meniscus injuries. These findings may represent an important foundation for developing a translational bio-active glue guiding the regenerative healing of meniscus injuries.

In situ cardiac regeneration by using neuropeptide substance P and IGF-1C peptide eluting heart patches

Cardiovascular diseases cause huge socio-economic burden worldwide.Although a mammalian myocardium has its own limited healing capability,scaffold materials capable of releasing stem cell recruiting/engrafting factors may facilitate the regeneration of the infarcted myocardium.The aim of this research was to develop cardiac patches capable of simultaneously eluting substance P(SP)and insulin-like growth factor-1C(IGF-1C)peptide.Polycaprolactone/collagen type 1-based patches with or without SP and IGF-1C peptide were fabricated by co-electrospinning,which exhibited nanofibrous morphology.SP and IGF-1C/SP patches recruited significantly higher numbers of bone marrow-mesenchymal stem cells than that of the negative control and patch-only groups in vitro.The developed patches were transplanted in an infarcted myocardium for up to 14 days.Mice underwent left anterior descending artery ligation and received one of the following treatments:(i)sham,(ii)saline,(iii)patch-only,(iv)IGF-1C patch,(v)SP patch and(vi)IGF-1C/SP patch.SP and IGF-1C/SP patch-treated groups exhibited better heart function and attenuated adverse cardiac remodeling than that of the saline,patch-only and individual peptide containing cardiac patches.SP patch and IGF-1C/SP patch-treated groups also showed higher numbers of CD31-positive vessels and isolectin B4-positive capillaries than that of other groups.IGF-1C/SP-treated group also showed thicker left ventricular wall in comparison to the saline and patch-only groups.Moreover,IGF-1C/SP patches recruited significantly higher numbers of CD29-positive cells and showed less numbers of Tunel-positive cells compared with the other groups.These data suggest that SP and IGF-1C peptides may act synergistically for in situ tissue repair.

Bioinspired Andrias davidianus-Derived wound dressings for localized drug-elution

Local drug delivery has received increasing attention in recent years.However,the therapeutic efficacy of local delivery of drugs is still limited under certain scenarios,such as in the oral cavity or in wound beds after resection of tumors.In this study,we introduce a bioinspired adhesive hydrogel derived from the skin secretions of Andrias davidianus(SSAD)as a wound dressing for localized drug elution.The hydrogel was loaded with aminoguanidine or doxorubicin,and its controlled drug release and healing-promoting properties were verified in a diabetic rat palatal mucosal defect model and a C57BL/6 mouse melanoma-bearing model,respectively.The results showed that SSAD hydrogels with different pore sizes could release drugs in a controllable manner and accelerate wound healing.Transcriptome analyses of the palatal mucosa suggested that SSAD could significantly upregulate pathways linked to cell adhesion and extracellular matrix deposition and had the ability to recruit keratinocyte stem cells to defect sites.Taken together,these findings indicate that property-controllable SSAD hydrogels could be a promising biofunctional wound dressing for local drug delivery and promotion of wound healing.

In situ bone regeneration with sequential delivery of aptamer and BMP2 from an ECM-based scaffold fabricated by cryogenic free-form extrusion

In situ tissue engineering is a powerful strategy for the treatment of bone defects.It could overcome the limitations of traditional bone tissue engineering,which typically involves extensive cell expansion steps,low cell survival rates upon transplantation,and a risk of immuno-rejection.Here,a porous scaffold polycaprolactone(PCL)/decellularized small intestine submucosa(SIS)was fabricated via cryogenic free-form extrusion,followed by surface modification with aptamer and PlGF-2_(123-144)*-fused BMP2(pBMP2).The two bioactive molecules were delivered sequentially.The aptamer Apt19s,which exhibited binding affinity to bone marrow-derived mesenchymal stem cells(BMSCs),was quickly released,facilitating the mobilization and recruitment of host BMSCs.BMP2 fused with a PlGF-2_(123-144)peptide,which showed“super-affinity”to the ECM matrix,was released in a slow and sustained manner,inducing BMSC osteogenic differentiation.In vitro results showed that the sequential release of PCL/SIS-pBMP2-Apt19s promoted cell migration,proliferation,alkaline phosphatase activity,and mRNA expression of osteogenesis-related genes.The in vivo results demonstrated that the sequential release system of PCL/SIS-pBMP2-Apt19s evidently increased bone formation in rat calvarial critical-sized defects compared to the sequential release system of PCL/SIS-BMP2-Apt19s.Thus,the novel delivery system shows potential as an ideal alternative for achieving cell-free scaffold-based bone regeneration in situ.