Stem cell homing-based tissue engineering using bioactive materials

Tissue engineering focuses on repairing tissue and restoring tissue functions by employing three elements： scaffolds, cells and biochemical signals. In tissue engineering, bioactive material scaffolds have been used to cure tissue and organ defects with stem cell-based therapies being one of the best documented approaches. In the review, different biomaterials which are used in several methods to fabricate tissue engineering scaffolds were explained and show good properties （biocompatibility, biodegradability, and mechanical properties etc.） for cell migration and infiltration. Stem cell homing is a recruitment process for inducing the migration of the systemically transplanted cells, or host cells, to defect sites. The mechanisms and modes of stem cell homing-based tissue engineering can be divided into two types depending on the source of the stem cells： endogenous and exogenous. Exogenous stem cell-based bioactive scaffolds have the challenge of long-term culturing in vitro and for endogenous stem cells the biochemical signal homing recruitment mechanism is not clear yet. Although the stem cell homing-based bioactive scaffolds are attractive candidates for tissue defect therapies, based on in vitro studies and animal tests, there is still a long way before clinical application.

Alkaline activation of endogenous latent TGFβ1 by an injectable hydrogel directs cell homing for in situ complex tissue regeneration

Utilization of the body’s regenerative potential for tissue repair is known as in situ tissue regeneration.However,the use of exogenous growth factors requires delicate control of the dose and delivery strategies and may be accompanied by safety,efficacy and cost concerns.In this study,we developed,for the first time,a biomaterial-based strategy to activate endogenous transforming growth factor beta 1(TGFβ1)under alkaline conditions for effective in situ tissue regeneration.We demonstrated that alkaline-activated TGFβ1 from blood serum,bone marrow fluids and soaking solutions of meniscus and tooth dentin was capable of increasing cell recruitment and early differentiation,implying its broad practicability.Furthermore,we engineered an injectable hydrogel(MS-Gel)consisting of gelatin microspheres for loading strong alkaline substances and a modified gelatin matrix for hydrogel click crosslinking.In vitro models showed that alkaline MS-Gel controllably and sustainably activated endogenous TGFβ1 from tooth dentin for robust bone marrow stem cell migration.More importantly,infusion of in vivo porcine prepared root canals with alkaline MS-Gel promoted significant pulp-dentin regeneration with neurovascular stroma and mineralized tissue by endogenous proliferative cells.Therefore,this work offers a new bench-to-beside translation strategy using biomaterial-activated endogenous biomolecules to achieve in situ tissue regeneration without the need for cell or protein delivery.

Therapeutic potential of bone marrow-derived mononuclear cells for experimental cerebral ischemia in mice

Bone marrow mononuclear cells （BMMCs） can be directly harvested from the donor, allowing for easier application compared with bone marrow mesenchymal stem cells. The present study hypothesized that BMMC transplantation could ameliorate cerebral ischemia in a mouse model. BMMCs were double-labeled with PKH26 and 4＇, 6-diamidino-2-phenylindole （DAPI）, followed by infusion into mice via the tail vein to induce focal cerebral ischemia. At 14 days after transplantation, morphological and neurofunctional recovery were analyzed. PKH26 and DAPI double-positive BMMCs were detected in the cerebral hemisphere of all transplantation mice. Following BMMC administration, there was significant difference in neurofunctional recovery, but no significant difference in survival rates between BMMC-treated mice and other mice. These results demonstrate that transplanted BMMCs migrate to brain tissue and promote neurological function recovery in a mouse model of cerebral ischemia.

Tooth regeneration: a revolution in stomatology and evolution in regenerative medicine

A tooth is a complex biological organ and consists of multiple tissues including the enamel, dentin, cementum and pulp. Tooth loss is the most common organ failure. Can a tooth be regenerated？ Can adult stem cells be orchestrated to regenerate tooth structures such as the enamel, dentin, cementum and dental pulp, or even an entire tooth？ If not, what are the therapeutically viable sources of stem cells for tooth regeneration？ Do stem cells necessarily need to be taken out of the body, and manipulated ex vivo before they are transplanted for tooth regeneration？ How can regenerated teeth be economically competitive with dental implants？ Would it be possible to make regenerated teeth affordable by a large segment of the population worldwide？ This review article explores existing and visionary approaches that address some of the above-mentioned questions. Tooth regeneration represents a revolution in stomatology as a shift in the paradigm from repair to regeneration： repair is by metal or artificial materials whereas regeneration is by biological restoration. Tooth regeneration is an extension of the concepts in the broad field of regenerative medicine to restore a tissue defect to its original form and function by biological substitutes.

Effect of Ermiao Fang with Xixin(Herba Asari Mandshurici) on bone marrow stem cell directional homing to a focal zone in an osteoarthritis rat model

OBJECTIVE: To investigate the effects of Ermiao Fang(EM) with medical guide Xixin(Herba Asari Mandshurici)(HAM) on bone marrow stem cell migration to a focal zone in osteoarthritis(OA) rats.METHODS: OA rats were induced by arthrectomy and assigned to sham-operated, model, EM, or EM plus HAM groups.All rats were injected with recombinant human granulocyte colony-stimulating factor 30μg·kg-1·d-1for7 days and treated with EMor EM plus HAM at 1.6 or 1.9 g·kg-1·d-1 for 3 or 6 weeks, respectively. Chondrocyte apoptosis and cartilage matrix components were tested by transferase-mediated deoxyuridine triphosphate-biotin nick end labeling assay and special staining. Levels of interleukin-1 beta(IL-1β) tumor necrosis factor alpha(TNF-α) nitric oxide(NO), and inducible nitric oxide synthase(iNOS) in serum were detected by enzyme-linked immunosorbent assay or radioimmunoassay. Matrix metalloproteinases(MMPs)-13,tissue inhibitors of metalloproteinases(TIMPs)-1,Bromodeoxyuridine(BrdU), cluster of differentiation 34(CD34), and stromal cell-derived factor 1(SDF-1) were measured by immunohistochemical assay.RESULTS:The EM and EM plus HAM groups had significantly less cartilage damage and synovium inflammation the model group. Moreover, the EM and EM plus HAM groups had less chondrocyte apoptosis and more proteoglycan and collagen content than the model group.The EM and EMplus HAM groups had obviously higher MMPs-13 and TIMPs-1 expression in the cartilage than the model group. Moreover, the two formula groups had less release of IL-1β, TNF-α, NO, and iNOS than model group. Importantly, the expressions of BrdU, CD34,and SDF-1 in cartilage were significantly higher in the EM and EM plus HAM-Medtreated rats than model group. Notably, the EM plus HAM treatment seemed to have the greatest effects.CONCLUSION: HAM improves the therapeutic effects of EM on OA rats by enhancing BMSC directional homing to the focal zone.

Effect of Chitin Treatment on Softening of Actinidia arguta

[Objectives] This study was conducted to discuss the effect of chitin treatment on softening of Actinidia arguta Huanyou No. 1 as the test material.[Methods]Huanyou No. 1 was sprayed with chitin,and the changes of some physiological and biochemical indexes in fruit softening were investigated. [Results]Chitin treatment significantly improved single fruit weight,increased soluble solid content,but decreased titratable acid content and significantly reduced the content of cellulose and hemicellulose; and the chitin treatment significantly inhibited the breakdown of pectin,cellulose and hemicellulose,and inhibited the activities of PG enzyme and β-Gal enzyme. [Conclusions] Chitin spray treatment could increase the yield of A. arguta,and improve its quality and storage property.