CD34 monoclonal antibody-immobilized electrospun polyurethane for the endothelialization of vascular grafts

Improving hemocompatibility in tissue-engineered products employing heparin-loaded nanoplatforms

The enhancement of hemocompatibility through the use of nanoplatforms loaded with heparin represents a highly desirable characteristic in the context of emerging tissue engineering applications. The significance of employing heparin in biological processes is unquestionable, owing to its ability to interact with a diverse range of proteins. It plays a crucial role in numerous biological processes by engaging in interactions with diverse proteins and hydrogels. This review provides a summary of recent endeavors focused on augmenting the hemocompatibility of tissue engineering methods through the utilization of nanoplatforms loaded with heparin. This study also provides a comprehensive review of the various applications of heparin-loaded nanofibers and nanoparticles, as well as the techniques employed for encapsulating heparin within these nanoplatforms. The biological and physical effects resulting from the encapsulation of heparin in nanoplatforms are examined. The potential applications of heparin-based materials in tissue engineering are also discussed, along with future perspectives in this field.

Evaluation of human umbilical vein endothelial cells growth onto heparin-modified electrospun vascular grafts

One of the main challenges of cardiovascular tissue engineering is the development of bioresorbable and compliant small-diameter vascular grafts (SDVG) for patients where autologous grafts are not an option. In this work, electrospun bilayered bioresorbable SDVG based on blends of poly(L-lactic acid) (PLLA) and segmented polyurethane (PHD) were prepared and evaluated. The inner layer of these SDVG was surface-modified with heparin, following a methodology involving PHD urethane functional groups. Heparin was selected as anticoagulant agent, and also due to its ability to promote human umbilical vein endothelial cells (HUVECs) growth and to inhibit smooth muscle cells over-proliferation, main cause of neointimal hyperplasia and restenosis. Immobilized heparin was quantified and changes in SDVG microstructure were investigated through SEM. Tensile properties of the heparin-functionalized SDVG resembled those of saphenous vein. Vascular grafts were seeded with HUVECs and cultured on a flow-perfusion bioreactor to analyze the effect of heparin on graft endothelization under simulated physiological-like conditions. The analysis of endothelial cells attachment and gene expression (Real-Time PCR) pointed out that the surface functionalization with heparin successfully promoted a stable and functional endothelial cell layer.

Surface-Modifying Polymers for Blood-Contacting Polymeric Biomaterials

Bulk blending is considered as one of the most effective and straightforward ways to improve the hemo-compatibility of blood-contacting polymeric biomaterials among many surface modification methods. Zwitterionic structure-, glycocalyx-like structure-, and heparin-like structure-based oligomers have been synthesized as additives and blended with base polymers to improve the blood compatibility of base polymers. Fluorinated end- and side-functionalized oligomers could promote the migration of functionalized groups to the surface of biomedical polymers without changing their bulk properties, and it highly depends on the number and concentration of functional groups. Moreover, oligomers having both zwitterion and fluorine are receiving considerable attention due to their desirable phase separation, which can avoid undesired protein adsorption and platelet adhesion. The surface analysis of the surface-modified materials is usually investigated by analytical tools such as contact angle measurement, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). Blood compatibility is mainly evaluated via platelet adhesion and protein adsorption test, and the result showed a significant decrease in the amount of undesirable adsorption. These analyses indicated that surface modification using bulk blending technique effectively improves blood compatibility of polymeric biomaterials.

State of the Art of Small-Diameter Vessel-Polyurethane Substitutes

Cardiovascular diseases are a severe threat to human health. Implantation of small-diameter vascular substitutes is a promising therapy in clinical operations. Polyurethane (PU) is considered one of the most suitable materials for this substitution due to its good mechanical properties, controlled biostability, and proper biocompatibility. According to biodegradability and biostability, in this review, PU small-diameter vascular substitutes are divided into two groups: biodegradable scaffolds and biostable prostheses, which are applied to the body for short- and long-term, respectively. Following this category, the degradation principles and mechanisms of different kinds of PUs are first discussed; then the chemical and physical methods for adjusting the properties and the research advances are summarized. On the basis of these discussions, the problems remaining at present are addressed, and the contour of future research and development of PU-based small-diameter vascular substitutes toward clinical applications is outlined.

An immunological electrospun scaffold for tumor cell killing and healthy tissue regeneration

Antibody-based cancer immune therapy has attracted lots of research interest in recent years; however, it is greatly limited by the easy distribution and burst release of antibodies. In addition, after the clearance of the tissue, healthy tissue regeneration is another challenge for cancer treatment. Herein, we have developed a specific immunological tissue engineering scaffold using the agonistic mouse anti-human CD40 antibody (CD40mAb) incorporated into poly(l-lactide) (PLLA) electrospun fibers through the dopamine (PDA) motif (PLLA-PDA-CD40mAb). CD40mAb is successfully incorporated onto the surface of the electrospun fibrous scaffold, which is proved by immunofluorescence staining, and the PLLA-PDA-CD40mAb scaffold has an anti-tumor effect by locally releasing CD40mAb. Therefore, this immunological electrospun scaffold has very good potential to be developed as a powerful tool for localized tumor treatment, and this is the first to be reported in this area.