The journey of decellularized vessel: from laboratory to operating room

Over the past few decades, there has been a remarkable advancement in the field of transplantation. But the shortage of donors is still an urgent problem that requires immediate attention. As with xenotransplantation, bioengineered organs are promising solutions to the current shortage situation. And decellularization is a unique technology in organ-bioengineering. However, at present, there is no unified decellularization method for different tissues, and there is no gold-standard for evaluating decellularization efficiency. Meanwhile, recellularization, re-endothelialization and modification are needed to form transplantable organs. With this mind, we can start with decellularization and re-endothelialization or modification of small blood vessels, which would serve to address the shortage of small-diameter vessels while simultaneously gathering the requisite data and inspiration for further recellularization of the whole organ-scale vascular network. In this review, we collect the related experiments of decellularization and post-decellularization approaches of small vessels in recent years. Subsequently, we summarize the experience in relation to the decellularization and post-decellularization combinations, and put forward obstacle we face and possible solutions.

Fabrication and performance evaluation of PLCL-hCOLIII small-diameter vascular grafts crosslinked with procyanidins

Cardiovascular disease has become one of the main causes of death. It is the common goal of researchers worldwide to develop small-diameter vascular grafts to meet clinical needs. Collagen is a valuable biomaterial that has been used in the preparation of vascular grafts and has shown good results. Recombinant humanized collagen (RHC) has the advantages of clear chemical structure, batch stability, no virus hazard and low immunogenicity compared with animal-derived collagen, which can be developed as vascular materials. In this study, Poly (l-lactide- ε-caprolactone) with l-lactide/ε-caprolactone (PLCL) and type III recombinant humanized collagen (hCOLIII) were selected as raw materials to prepare vascular grafts, which were prepared by the same-nozzle electrospinning apparatus. Meanwhile, procyanidin (PC), a plant polyphenol, was used to cross-link the vascular grafts. The physicochemical properties and biocompatibility of the fabricated vascular grafts were investigated by comparing with glutaraldehyde (GA) crosslinked vascular grafts and pure PLCL grafts. Finally, the performance of PC cross-linked PLCL-hCOLIII vascular grafts were evaluated by rabbit carotid artery transplantation model. The results indicate that the artificial vascular grafts have good cell compatibility, blood compatibility, and anti-calcification performance, and can remain unobstructed after 30 days carotid artery transplantation in rabbits. The grafts also showed inhibitory effects on the proliferation of SMCs and intimal hyperplasia, demonstrating its excellent performance as small diameter vascular grafts.

The application of composite scaffold materials based on decellularized vascular matrix in tissue engineering: a review

Decellularized vascular matrix is a natural polymeric biomaterial that comes from arteries or veins which are removed the cellular contents by physical, chemical and enzymatic means, leaving only the cytoskeletal structure and extracellular matrix to achieve cell adhesion, proliferation and differentiation and creating a suitable microenvironment for their growth. In recent years, the decellularized vascular matrix has attracted much attention in the field of tissue repair and regenerative medicine due to its remarkable cytocompatibility, biodegradability and ability to induce tissue regeneration. Firstly, this review introduces its basic properties and preparation methods; then, it focuses on the application and research of composite scaffold materials based on decellularized vascular matrix in vascular tissue engineering in terms of current in vitro and in vivo studies, and briefly outlines its applications in other tissue engineering fields; finally, it looks into the advantages and drawbacks to be overcome in the application of decellularized vascular matrix materials. In conclusion, as a new bioactive material for building engineered tissue and repairing tissue defects, decellularized vascular matrix will be widely applied in prospect.

Improved hemocompatibility by modifying acellular blood vessels with bivalirudin and its biocompatibility evaluation

The incidence rate of cardiovascular diseases is increasing year by year. The demand for coronary artery bypass grafting has been very large. Acellular blood vessels have potential clinical application because of their natural vascular basis, but their biocompatibility and anticoagulant energy need to be improved. We decellularized the abdominal aorta of SD rats, and then modified with bivalirudin via polydopamine. The mechanical properties, blood compatibility, cytocompatibility, immune response, and anticoagulant properties were evaluated, and then the bivalirudin-modified acellular blood vessels were implanted into rats for remodeling evaluation in vivo. The results we got show that the bivalirudin-modified acellular blood vessels showed good cytocompatibility and blood compatibility, and its anti-inflammatory trend was dominant in the immune response. After 3 months of transplantation, the bivalirudin-modified acellular blood vessels did not easily form thrombus. It was not easy to form calcification and could make the host cells grow better. Through vascular stimulation and immunofluorescence test, we found that vascular smooth muscle cells and endothelial cells proliferated well in the bivalirudin group. Bivalirudin-modified acellular blood vessels provided new idea for small diameter tissue engineering blood vessels, and may become a potential clinical substitute for small-diameter vascular grafts.

Study of tissue engineered vascularised oral mucosa-like structures based on ACVM-0.25% HLC-I scaffold in vitro and in vivo

PURPOSE

To explore the feasibility of constructing tissue-engineered vascularised oral mucosa-like structures with rabbit ACVM-0.25% HLC-I scaffold and human gingival fibroblasts (HGFs), human gingival epithelial cells (HGECs) and vascular endothelial-like cells (VEC-like cells).

METHOD

Haematoxylin and Eosin (H&E) staining, immunohistochemical, immunofluorescence, 5-ethynyl-2'-deoxyuridine (EdU) staining and scanning electron microscope (SEM) were performed to detect the growth status of cells on the scaffold complex. After the scaffold complex implanted into nude mice for 28 days, tissues were harvested to observe the cell viability and morphology by the same method as above. Additionally, biomechanical experiments were used to assess the stability of composite scaffold.

RESULTS

Immunofluorescence and Immunohistochemistry showed positive expression of Vimentin, S100A₄ and CK, and the induced VEC-like cells had the ability to form tubule-like structures. In vitro observation results showed that HGFs, HGECs and VEC-like had good compatibility with ACVM-0.25% HLC-I and could be layered and grow in the scaffold. After implanted, the mice had no immune rejection and no obvious scar repair on the body surface. The biomfechanical test results showed that the composite scaffold has strong stability.

CONCLUSION

The tissue-engineered vascularised complexes constructed by HGFs, HGECs, VEC-like cells and ACVM-0.25% HLC-I has good biocompatibility and considerable strength.

Applications of decellularized materials in tissue engineering: advantages, drawbacks and current improvements, and future perspectives

Decellularized materials (DMs) are attracting more and more attention in tissue engineering because of their many unique advantages, and they could be further improved in some aspects through various means.

Characterization of different biodegradable scaffolds in tissue engineering

The aim of the present study was to compare the characteristics of acellular dermal matrix (ADM), small intestinal submucosa (SIS) and Bio‑Gide scaffolds with acellular vascular matrix (ACVM)‑0.25% human‑like collagen I (HLC‑I) scaffold in tissue engineering blood vessels. The ACVM‑0.25% HLC‑I scaffold was prepared and compared with ADM, SIS and Bio‑Gide scaffolds via hematoxylin and eosin (H&E) staining, Masson staining and scanning electron microscope (SEM) observations. Primary human gingival fibroblasts (HGFs) were cultured and identified. Then, the experiment was established via the seeding of HGFs on different scaffolds for 1, 4 and 7 days. The compatibility of four different scaffolds with HGFs was evaluated by H&E staining, SEM observation and Cell Counting Kit‑8 assay. Then, a series of experiments were conducted to evaluate water absorption capacities, mechanical abilities, the ultra‑microstructure and the cytotoxicity of the four scaffolds. The ACVM‑0.25% HLC‑I scaffold was revealed to exhibit the best cell proliferation and good cell architecture. ADM and Bio‑Gide scaffolds exhibited good mechanical stability but cell proliferation was reduced when compared with the ACVM‑0.25% HLC‑I scaffold. In addition, SIS scaffolds exhibited the worst cell proliferation. The ACVM‑0.25% HLC‑I scaffold exhibited the best water absorption, followed by the SIS and Bio‑Gide scaffolds, and then the ADM scaffold. In conclusion, the ACVM‑0.25% HLC‑I scaffold has good mechanical properties as a tissue engineering scaffold and the present results suggest that it has better biological characterization when compared with other scaffold types.

Resveratrol inhibits paclitaxel-induced neuropathic pain by the activation of PI3K/Akt and SIRT1/PGC1α pathway

Background

Phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) is one of the essential signaling pathways for the development and maintenance of neuropathic pain.

Objective

To investigate the effect of resveratrol (RES) on paclitaxel-induced neuropathic pain in rats and elucidate the underlying molecular mechanisms.

Method

Male Sprague Dawley rats were randomly divided into seven groups (n=10/group): Group C, Group P, Group R, Group R+P, Group LY + R+P, Group LY (the specific inhibitor of PI3K), Group E (the specific inhibitor of sirtuin 1 [SIRT1]). Paw withdrawal mechanical threshold (PWT) and thermal withdrawal latency (TWL) were recorded. Mitochondrial histomorphology was performed by transmission electron microscope. PI3K, p-Akt, and t-Akt expressions were tested using immunohistochemistry. Western blot was used to detect p-Akt, t-Akt, SIRT1, and PGC1α expressions. The apoptosis in the striatum, spinal dorsal horns (SDH), and dorsal root ganglions (DRG) tissues was assayed by TUNEL. ELISA was used to detect the contents of IL-β, IL-10, malondialdehyde (MDA), and superoxide dismutase (SOD) in striatum, SDH, and DRG tissues.

Results

Compared to the control group, PWT and TWL in the P and LY +R+P groups were significantly decreased on 8th and 14th day after paclitaxel administration (P<0.05). The expressions of p-Akt, SIRT1, and PGC1α were decreased in paclitaxel-induced neuropathic rats; however, the expressions of p-Akt, SIRT1, and PGC1α were significantly increased after RES treatment (P<0.05). Furthermore, the expression of p-Akt was decreased by LY294002 (P<0.05), and amount of SIRT1 and PGC1α expression was inhibited by EX-527 (P<0.05). The t-Akt level was not significantly changed in all groups. RES prevented paclitaxel-induced mitochondrial damage by PI3K/Akt. RES improves the pain symptoms of paclitaxel neuralgia rats by increasing the IL-10 and decreasing the expression of IL-1β. RES increases the SOD and reduces the MDA. RES reduces apoptosis by SIRT1/PGC1α signal pathway.

Conclusion

Our results suggest that RES may inhibit paclitaxel-induced neuropathic pain via PI3K/Akt and SIRT1/PGC1α pathways.