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.
To reduce thrombosis risk on small diameter (<6 mm) vascular grafts, hyaluronic acid is coated on the lumen of decellularized tissue engineered vascular grafts. This layer effectively shields platelets from collagen‐triggered activation, while allowing endothelial repopulation over time in vivo. Hence, hyaluronic acid–coated grafts may be an off‐the‐shelf small‐diameter vascular graft with dual benefits: antithrombogenic protection and promotion of endothelium.
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 tenfold 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. X-ray photoelectron spectroscopy, nuclear magnetic resonance imaging, mass spectrometry and Fourier transform infrared FTIR spectroscopy were used to characterize the synthesis steps, building the final heparin layered coatings. The continuity of the heparin coating was verified using fluorescent microscopy and histological analysis. The efficacy of heparin linkage was demonstrated with factor Xa anti-thrombogenic 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.
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 ...many 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.
We have developed novel, easy-to-use, in vitro assays that directly quantify live endothelialized surface's functional heparin weights and their anticoagulant capacity to inactivate Factor Xa and thrombin. Using our assays, we characterized 2 commonly used vascular models: native rat aorta and cultured human umbilical vein endothelial cell monolayer. We determined heparin contents to be ≈10 000 ng/cm(2) on the native aorta and ≈10-fold lower on cultured human umbilical vein endothelial cells. Interestingly, human umbilical vein endothelial cells demonstrated a 5-fold lower anticoagulation 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 liquid chromatography-mass spectrometry analysis.
Our assays are of high relevance in the vascular community because they can be used to establish the antithrombogenic 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.
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 DNA, biochemical composition, mechanical characteristics, tissue architecture, and recellularization capacity.
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 DNA, biochemical composition, mechanical characteristics, tissue architecture, and recellularization capacity.
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.
Objective: To determine the optimal protective hypothermia in arrested hearts.Methods: Pig hearts in vivo infused with cardiopulmonary bypass; Myocardial velocity (V max) and left ventricular dP/dt ...max (dP/dt max )was used to present contractility A heart arrested patient treated with 32 degree C cooling protocol.(Kupchik NL:Crit Care Med 37SuppllS279,2009).Results: 17 hearts arrested 60 min with 29‐35°C. At 60 min of reperfusion (20 min of off‐pump), the recovery of Vmax and dP/dtmax show sigmoid curves that consist two plateaus: a good recovery plateau at 29 ‐30°C and a poor recovery plateau at 34 ‐35°C (p<0.05). There exists a point of inflection at the right side of the high recovery plateau. That point should be the optimal protective hypothermia (Figure 1). One of the authors suffered from a sudden cardiac arrest more than 6 min. He was treated with hypothermic rescue (32°C ) resulted a full recovery. Conclusion: Around 30.5°C is an optimal protective hypothermia for arrested heart.
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Grant Funding Source: Partial support from NIH HL‐60666 and CHRMC HR‐5836.
Many therapeutic hypothermia recommendations have been reported, but the information supporting them is sparse, and reveals a need for the data of target therapeutic hypothermia (TTH) from ...well-controlled experiments. The core temperature ≤35°C is considered as hypothermia, and 29°C is a cooling injury threshold in pig heart in vivo. Thus, an optimal protective hypothermia (OPH) should be in the range 29-35°C. This study was conducted with a pig cardiopulmonary bypass preparation to decrease the core temperature to 29-35°C range at 20 minutes before and 60 minutes during heart arrest. The left ventricular (LV) developed pressure, maximum of the first derivative of LV (dP/dtmax), cardiac power, heart rate, cardiac output, and myocardial velocity (Vmax) were recorded continuously via an LV pressure catheter and an aortic flow probe. At 20 minutes of off-pump during reperfusion after 60 minutes arrest, 17 hypothermic hearts showed that the recovery of Vmax and dP/dtmax established sigmoid curves that consisted of two plateaus: a good recovery plateau at 29-30.5°C, the function recovered to baseline level (BL) (Vmax=118.4%±3.9% of BL, LV dP/dtmax=120.7%±3.1% of BL, n=6); another poor recovery plateau at 34-35°C (Vmax=60.2%±2.8% of BL, LV dP/dtmax=28.0%±5.9% of BL, p<0.05, n=6; ), which are similar to the four normothermia arrest (37°C) hearts (Vmax=55.9%±4.8% of BL, LV dP/dtmax=24.5%±2.1% of BL, n=4). The 32-32.5°C arrest hearts showed moderate recovery (n=5). A point of inflection (around 30.5-31°C) existed at the edge of a good recovery plateau followed by a steep slope. The point presented an OPH that should be the TTH. The results are concordant with data in the mammalian hearts, suggesting that the TTH should be initiated to cool core temperature at 31°C.
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