This review provides an overview of the incorporation of heparin into biomaterials with a focus on drug delivery and the use of heparin-based biomaterials for self-assembly of polymer networks. ...Heparin conjugation to biomaterials was originally explored to reduce the thrombogenicity of materials in contact with blood. Many of the conjugation strategies that were developed for these applications are still popular today for other applications. More recently heparin has been conjugated to biomaterials for drug delivery applications. Many of the delivery approaches have taken advantage of the ability of heparin to bind to a wide variety of growth factors, protecting them from degradation and potentiating interactions with cell surface receptors. More recently, the use of heparin as a base polymer for scaffold fabrication has also been explored, often utilizing non-covalent binding of heparin with peptides or proteins to promote self-assembly of hydrogel networks. This review will highlight recent advances in each of these areas.
Abstract Benefits of a direct anterior approach (DAA) versus a posterior-lateral (PA) approach to THA were assessed in a single-surgeon, IRB-approved, prospective, randomized clinical study. Subjects ...(43 DAA and 44 PA) were evaluated at 6 weeks, and 3, 6 and 12 months. The primary end point was ability to climb stairs normally and walk unlimited at each time point. Secondary end points included assessment by several outcome instruments. DAA subjects performed better during the immediate post-operative period; they had lower VAS pain scores on the first post-operative day, more subjects climbing stairs normally and walking unlimited at 6 weeks, and higher HOOS Symptoms scores at 3 months. There were no significant differences between groups at later time points. Findings confirm previous reports of benefits of DAA versus PA in early post-operative phases.
Nerve injuries can be life-long debilitating traumas that severely impact patients' quality of life. While many acellular neural scaffolds have been developed to aid the process of nerve ...regeneration, complete functional recovery is still very difficult to achieve, especially for long-gap peripheral nerve injury and most cases of spinal cord injury. Cell-based therapies have shown many promising results for improving nerve regeneration. With recent advances in neural tissue engineering, the integration of biomaterial scaffolds and cell transplantation are emerging as a more promising approach to enhance nerve regeneration. This review provides an overview of important considerations for designing cell-carrier biomaterial scaffolds. It also discusses current biomaterials used for scaffolds that provide permissive and instructive microenvironments for improved cell transplantation.
This study investigated whether delayed treatment of spinal cord injury with controlled release of neurotrophin-3 (NT-3) from fibrin scaffolds can stimulate enhanced neural fiber sprouting. Long ...Evans rats received a T9 dorsal hemisection spinal cord injury. Two weeks later, the injury site was re-exposed, and either a fibrin scaffold alone, a fibrin scaffold containing a heparin-based delivery system with different concentrations of NT-3 (500 and 1,000 ng/mL), or a fibrin scaffold containing 1,000 ng/mL of NT-3 (no delivery system) was implanted into the injury site. The injured spinal cords were evaluated for morphological differences using markers for neurons, astrocytes, and chondroitin sulfate proteoglycans 2 weeks after treatment. The addition of 500 ng/mL of NT-3 with the delivery system resulted in an increase in neural fiber density compared to fibrin alone. These results demonstrate that the controlled release of NT-3 from fibrin scaffolds can enhance neural fiber sprouting even when treatment is delayed 2 weeks following injury. Biotechnol. Bioeng. 2009; 104: 1207-1214.
Enriched in glycolytic enzymes, paucicellular and hypovascular intrasynovial flexor tendons fail to mount an effective healing response after injury and repair. In contrast, well‐vascularized ...extrasynovial flexor tendons possess high levels of oxidative phosphorylation (OXPHOS) enzymes and have a markedly improved healing capacity. This study was designed to compare the metabolic profiles of the two types of tendons and to evaluate the impact of metabolic reprogramming on early intrasynovial tendon healing in a clinically relevant canine model. Results showed that healthy intrasynovial tendons expressed higher levels of PDK1 and GAPDH and lower levels of SCX and IGF1 than did extrasynovial tendons. PDK1 encodes a subtype of pyruvate dehydrogenase kinase (PDK) that inhibits OXPHOS. Consistently, ATP production via glycolysis was favored in intrasynovial tendon cells whereas OXPHOS was the preferred pathway in extrasynovial tendon cells. Inhibition of glycolysis in vitro increased SCX expression in intrasynovial tendon cells. Therefore, dichloroacetate (DCA), a PDK1 inhibitor, was used in vivo to shift intrasynovial tendon ATP production from glycolysis to OXPHOS. Oral DCA administration reduced serum lactate concentration and increased acetyl‐CoA content in repaired intrasynovial tendons and led to reduced TLR4 and IL1B and increased IGF1, SCX, and TGFB3 expressions in treated intrasynovial tendons compared to controls. Immunohistochemistry staining with anti‐Ki67 and anti‐CD31 antibodies revealed marked increases in cellularity and neovascularization in treated intrasynovial tendons. Clinical significance: The findings of this experiment indicate that improved gene expression and histological outcomes can be achieved by regulating glucose metabolism in the early stages following intrasynovial tendon repair.
In phytophagous insects, the larval host plant may have a profound effect on the biology of the adult stage. This influence has been most widely studied in females, where larval diet may affect their ...fecundity and survival. Males have been less well studied, with focus on host plant effects on (1) male size and the consequences of variable male size on male mating success, ejaculate, and/or nuptial gifts, or (2) male‐produced chemical signals important in sexual communication. The melon fly, Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae), is a world‐wide agricultural pest that infests plants of the family Cucurbitaceae primarily but also attacks hosts in other unrelated families. The objective of the present study was to investigate whether larval host influenced female choice in Z. cucurbitae and, in particular, test for random mating using adults (Z flies) whose larvae fed on a cucurbit host (zucchini, Cucurbita pepo L.) and adults (P flies) whose larvae fed on a non‐cucurbit host (papaya, Carica papaya L., Caricaceae). In field tent trials, both Z and P females mated more often with Z males than P males, and in no‐choice laboratory cage trials, mating latency was generally shorter for Z than for P males. Wing vein measurements, made both within and between generations, showed that Z males were consistently larger than P males. Further observations of fly trios — one female plus one large and one small male — revealed that large males dominated in aggressive encounters and exhibited wing fanning (signaling) more often than their smaller counterparts. Although olfactory signals associated with wing fanning were not investigated in the present study, the observed host‐mediated difference in male size is, if not solely responsible, certainly an important determinant of the mating patterns described.
In phytophagous insects, the larval host plant may have a profound effect on the biology of the adult stage. This influence has been most widely studied in females, where larval diet may affect their fecundity and survival. Males have been less well studied. In field tent trials and no‐choice laboratory cage trials, the larval host – zucchini vs. papaya – of melon fly, Zeugodacus cucurbitae (Diptera: Tephritidae), was found to affect adult size, which in turn influenced male mating success.
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