Michael Vivian Sefton

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Our failure to produce truly non-thrombogenic materials may reflect a failure to fully understand the mechanisms of biomaterial-associated thrombosis. The community has focused on minimizing coagulation or minimizing platelet adhesion and activation. We have infrequently considered the interactions between the two although we are generally familiar with(More)
In the laboratory environment where biomaterials are synthesized and their biocompatibility assessed, we find that endotoxin contamination is hard to avoid and must not be ignored. In those relatively few cases where endotoxin was known to be present, it has been clearly shown that endotoxin can significantly affect the biological response observed and(More)
MicroRNAs are known to play regulatory roles in gene expression associated with cancer development. We analyzed levels of the microRNA miR-24 in patients with breast carcinoma and found that miR-24 was higher in breast carcinoma samples than in benign breast tissues. We generated constructs expressing miR-24 and studied its functions using both in vitro and(More)
Tissue engineering is one approach to address the donor-organ shortage, but to attain clinically significant viable cell densities in thick tissues, laboratory-constructed tissues must have an internal vascular supply. We have adopted a biomimetic approach and assembled microscale modular components, consisting of submillimeter-sized collagen gel rods(More)
While stem cell transplantation could potentially treat a variety of disorders, clinical studies have not yet demonstrated conclusive benefits. This may be partly because transplanted stem cells have low survival rates, potentially due to host inflammation. The system described herein used two different gene therapy techniques to improve retention of rat(More)
We introduce the microfluidic organoids for drug screening (MODS) platform, a digital microfluidic system that is capable of generating arrays of individually addressable, free-floating, three-dimensional hydrogel-based microtissues (or 'organoids'). Here, we focused on liver organoids, driven by the need for early-stage screening methods for hepatotoxicity(More)
Are truly inert biomaterials feasible? Recent mathematical models of coagulation which are reviewed here suggest that such materials are impossible. This conclusion, which is certainly consistent with our collective experimental evidence, arises from the calculation that conversion of Factor XI to XIa never drops to zero even at the highest flow rates and(More)
Angiopathies are one of the leading underlying causes of morbidity in diabetic patients. Poorly managed blood glucose levels contribute to vascular defects that manifest themselves in numerous different clinical conditions, including diabetic retinopathy, nephropathy, peripheral artery disease, and compromised wound healing. The angiopoietin family (Angs(More)
Polyvinyl alcohol (PVA) coated onto polyethylene (PE) tubes exposed to human serum for 1 hour at 37 degrees C resulted in the production of 1.03 +/- 0.04 microg/cm2 of the soluble form of the terminal membrane attack complex, SC5b-9. This was approximately 20 x that produced by the polyethylene. About one quarter of this total was found associated with the(More)
Because the lack of thromboresistant vascular biomaterials is in part due to platelet activation, we have attempted, by using fluorescence-activated flow cytometry, to fully characterize the platelet population after in vitro material contact with whole blood. We have used a very simple, near-physiologic system whereby whole blood, anticoagulated with(More)