There is a growing body of work dedicated to producing acellular lung scaffolds for use in regenerative medicine by decellularizing donor lungs of various species. These scaffolds typically undergo substantial matrix damage due to the harsh conditions required to remove cellular material (e.g., high pH, strong detergents), lengthy processing times, or pre-existing tissue contamination from microbial colonization. In this work, a new decellularization technique is described that maintains the global tissue architecture, key matrix components, mechanical composition and cell-seeding potential of lung tissue while effectively removing resident cellular material. Acellular lung scaffolds were produced from native porcine lungs using a combination of Triton X-100 and sodium deoxycholate (SDC) at low concentrations in 24 hours. We assessed the effect of matrix decellularization by measuring residual

A novel method enabling the engineering of a dense and appropriately oriented heparin-containing layer on decellularized aortas has been developed. Amino groups of decellularized aortas were first modified to azido groups using 3-azidobenzoic acid. Azide-clickable dendrons were attached onto the azido groups through “alkyne-azide” click chemistry, affording a ten-fold amplification of adhesions sites. Dendron end groups were finally decorated with end-on modified heparin chains. Heparin chains were oriented like heparan sulfate groups on native endothelial cells surface. XPS, NMR, MS and FTIR were used to characterize the synthesis steps, building the final heparin layered coatings. Continuity of the heparin coating was verified using fluorescent microscopy and histological analysis. Efficacy of heparin linkage was demonstrated with factor Xa antithrombogenic assay and platelet adhesion studies. The results suggest that oriented heparin immobilization to decellularized aortas may improve the in vivo blood compatibility of decellularized aortas and vessels.

Novel biological vascular conduits, such as decellularized tissue engineered vascular grafts (TEVGs) are hindered by high thrombogenicity. To mimic the antithrombogenic surface of native vessels with a continuous glycosaminoglycan layer that is present on endothelial cells (ECs), a hyaluronic acid (HA) modified surface is established, to effectively shield blood platelets from collagen‐triggered activation. Using the amine groups present on 4 mm diameter decellularized TEVGs, a continuous HA hydrogel coating is built via a bifunctional thiol‐reactive cross‐linker, thereby avoiding nonspecific collagen matrix cross‐linking. The HA hydrogel layer recreates a luminal wall, “hiding” exposed collagen from the bloodstream. In vitro blood tests show that adhered platelets, fibrinogen absorption, and fibrin formation on HA‐coated decellularized TEVGs are significantly lower than on uncoated decellularized TEVGs. The HA surface also inhibits macrophage adhesion in vitro. HA‐coated decellularized syngeneic rat aortae (≈1.5 mm diameter), and TEVGs in rat and canine models, respectively, are protected from aggressive thrombus formation, and preserve normal blood flow. Re‐endothelialization is also observed. HA‐coated TEVGs may be an off‐the‐shelf small‐diameter vascular graft with dual benefits: antithrombogenic protection and promotion of endothelium.

Objective It is widely accepted that the presence of a glycosaminoglycan-rich glycocalyx is essential for endothelialized vasculature health; in fact, a damaged or impaired glycocalyx has been demonstrated in a number of vascular diseases. Currently, there are no methods that characterize glycocalyx functionality, thus limiting investigators’ ability to assess the role of the glycocalyx in vascular health. Approach and Results We have developed novel easy to use in vitro assays that directly quantify live endothelialized surface’s functional heparin weights and their anti-coagulant capacity to inactivate Factor Xa and thrombin. Using our assays, we characterized two commonly used vascular models: native rat aorta and cultured human umbilical vein endothelial cell (HUVEC) monolayer. We determined heparin contents to be about 10,000 ng/cm2 on the native aorta, and about ten-fold lower on cultured HUVECs. Interestingly HUVECs demonstrated a five-fold lower anti-coagulation capacity in inactivating both Factor Xa and thrombin relative to native aortas. We verified the validity and accuracy of the novel assays developed in this work using LC-MS analysis. Conclusions Our assays are of high relevance in the vascular community as they can be utilized to establish the anti-thrombogenic capacity of many different types of surfaces such as vascular grafts and transplants. This work will also advance the capacity for glycocalyx-targeting therapeutics development to treat damaged vasculatures.