Shape-Anisotropic Microembolics Generated by Microfluidic Synthesis for Transarterial Embolization Treatment.

Particulate embolic agents with calibrated sizes, which employ interventional procedures to achieve endovascular embolization, have recently attracted tremendous interest in therapeutic embolotherapies for a wide plethora of diseases. However, the particulate shape effect, which may play a critical role in embolization performances, has been rarely investigated. Here, polyvinyl alcohol (PVA)-based shape-anisotropic microembolics are developed using a facile droplet-based microfluidic fabrication method via heat-accelerated PVA-glutaraldehyde crosslinking reaction at a mild temperature of 38 ° C. Precise geometrical controls of the microembolics are achieved with a nearly capsule shape through regulating surfactant concentration and flow rate ratio between dispersed phase and continuous phase in the microfluidics. Two specific models are employed, i.e., in vitro decellularized rabbit liver embolization model and in vivo rabbit ear embolization model, to systematically evaluate the embolization behaviors of the nonspherical microembolics. Compared to microspheres of the same volume, the elongated microembolics demonstrated advantageous endovascular navigation capability, penetration depth and embolization stability due to their comparatively smaller radial diameter and their central cylindrical part providing larger contact area with distal vessels. Such nonspherical microembolics present a promising platform to apply shape anisotropy to achieve distinctive therapeutic effects for endovascular treatments.

Construction and performance evaluation of Hep/silk-PLCL composite nanofiber small-caliber artificial blood vessel graft.

To meet the growing clinical demand for small-caliber blood vessel grafts to treat cardiovascular diseases, it is necessary to develop safe and long-term unobstructed grafts. In this study, a biodegradable graft made of composite nanofibers is introduced. A composite nanofiber core-shell structure was prepared by a combination of conjugate electrospinning and freeze-dry technology. The core fiber was poly(l-lactide-co-caprolactone) (PLCL)-based and the core fibers were coated with heparin/silk gel, which acted as a shell layer. This special structure in which the core layer was made of synthetic materials and the shell layer was made of natural materials took advantage of these two different materials. The core PLCL nanofibers provided mechanical support during vascular reconstruction, and the shell heparin/silk gel layer enhanced the biocompatibility of the grafts. Moreover, the release of heparin in the early stage after transplantation could regulate the microenvironment and inhibit the proliferation of intima. All of the graft materials were biodegradable and safe biomaterials, and the degradation of the graft provided space for the growth of regenerated tissue in the late stage of transplantation. Animal experiments showed that the graft remained unobstructed for more than eight months in vivo. In addition, the regenerated vascular tissue provided a similar function to that of autogenous vascular tissue when the graft was highly degraded. Thus, the proposed method produced a graft that could maintain long-term patency in vivo and remodel vascular tissue successfully.

A biodegradable multifunctional nanofibrous membrane for periodontal tissue regeneration.

Biomaterial-based membranes represent a promising therapeutic option for periodontal diseases. Although conventional periodontal membranes function greatly in preventing the ingrowth of both fibroblasts and epithelial cells as well as connective tissues, they are not capable of promoting periodontal tissue regeneration. Here, we report a multifunctional periodontal membrane prepared by electrospinning biodegradable polymers with magnesium oxide nanoparticles (nMgO). nMgO is a light metal-based nanoparticle with high antibacterial capacity and can be fully resorbed in the body. Our results showed that incorporating nMgO into poly(L-lactic acid) (PLA)/gelatin significantly improved the overall properties of membranes, including elevated tensile strength to maintain structural stability and adjusted degradation rate to fit the time window of periodontal regeneration. Acidic degradation products of PLA were neutralized by alkaline ions from nMgO hydrolysis, ameliorating pH microenvironment beneficial for cell proliferation. In vitro studies demonstrated considerable antibacterial and osteogenic properties of nMgO-incorporated membranes that are highly valuable for periodontal regeneration. Further investigations in a rat periodontal defect model revealed that nMgO-incorporated membranes effectively guided periodontal tissue regeneration. Taken together, our data indicate that nMgO-incorporated membranes might be a promising therapeutic option for periodontal regeneration. STATEMENT OF SIGNIFICANCE: Traditional clinical treatments of periodontal diseases largely focus on the management of the pathologic processes, which cannot effectively regenerate the lost periodontal tissue. GTR, a classic method for periodontal regeneration, has shown promise in clinical practice. However, the current membranes might not fully fulfill the criteria of ideal membranes. Here, we report bioabsorbable nMgO-incorporated nanofibrous membranes prepared by electrospinning to provide an alternative for the clinical practice of GTR. The membranes not only function greatly as physical barriers but also exhibit high antibacterial and osteoinductive properties. We therefore believe that this study will inspire more practice work on the development of effective GTR membranes for periodontal regeneration.