Thermo-sensitive assembly of the biomaterial REP reduces hematoma volume following collagenase-induced intracerebral hemorrhage in rats.

Intracerebral hemorrhage (ICH) frequently results in severe disabilities and high mortality. RGD-containing elastin-like polypeptide (REP), a modified elastin-like polypeptide (ELP), is a thermally responsive biopolymer. REP has high affinity for cells and is known to show non-immunotoxicity, -cytotoxicity, and -inflammatory responses. Here we found that administration of REP in the acute phase of the ICH rat model reduced the hematoma volume, decreased the number of activated microglia, attenuated the expression of von Willebrand Factor (vWF), and prevented the leakage of immunoglobulin G (IgG) into the cerebral parenchyma without any occlusion of intact microvessels. Therefore, the present data suggest that REP treatment could be a novel therapeutic strategy for attenuating the acute phase of ICH.

Treatment of Burn and Surgical Wounds With Recombinant Human Tropoelastin Produces New Elastin Fibers in Scars.

Tropoelastin (TE), the soluble precursor of insoluble elastin fibers, is produced in minimal amounts in adults. Burn injuries result in inflexible collagen-rich scars because of lack of elastin fiber formation. We studied the feasibility of using recombinant human tropoelastin to enable elastin fiber production in burn and surgical scars to improve skin flexibility. In a swine hypertrophic burn scar model, normal skin and 3 × 3-cm partial thickness thermal burns underwent dermatome resection at 1 week post burn and randomized to four subcutaneous injections of saline or TE (either 0.5, 5, or 10 mg/ml) spaced 3 days apart. Two burn sites received TE injections after wound closure (0.5 or 10 mg/ml). At 90 days, skin hardness, flexibility, and histology were evaluated. All injury sites developed hypertrophic scars. New elastin fibers were found in burn scars in all injuries injected after skin closure with low (5/5) and high (6/6) TE doses (P < .05). No elastin fibers were observed without TE treatment. No significant differences in skin hardness, flexibility, or inflammation were observed. This is the first report demonstrating that subcutaneous injections of TE into surgical and burn injuries can safely produce new elastin fibers in scars. Despite the development of new elastin fibers, skin flexibility was not improved, possibly because of insufficient elastin fiber maturation or the hypertrophic model used. The ability to restore elastin fiber formation in adult skin after burns, trauma, and surgery may improve skin regeneration and reduce disabling complications of scar formation.

An activation-specific platelet inhibitor that can be turned on/off by medically used hypothermia.

OBJECTIVE: Therapeutic hypothermia is successfully used, for example, in cardiac surgery to protect organs from ischemia. Cardiosurgical procedures, especially in combination with extracorporeal circulation, and hypothermia itself are potentially prothrombotic. Despite the obvious need, the long half-life of antiplatelet drugs and thus the risk of postoperative bleedings have restricted their use in cardiac surgery. We describe here the design and testing of a unique recombinant hypothermia-controlled antiplatelet fusion protein with the aim of providing increased safety of hypothermia, as well as cardiac surgery. METHODS AND RESULTS: An elastin-mimetic polypeptide was fused to an activation-specific glycoprotein (GP) IIb/IIIa-blocking single-chain antibody. In silico modeling illustrated the sterical hindrance of a ß-spiral conformation of elastin-mimetic polypeptide preventing the single-chain antibody from inhibiting GPIIb/IIIa at 37°C. Circular dichroism spectra demonstrated reverse temperature transition, and flow cytometry showed binding to and blocking of GPIIb/IIIa at hypothermic body temperature (≤32°C) but not at normal body temperature. In vivo thrombosis in mice was selectively inhibited at hypothermia but not at 37°C. CONCLUSIONS: This is the first description of a broadly applicable pharmacological strategy by which the activity of a potential drug can be controlled by temperature. In particular, this drug steerability may provide substantial benefits for antiplatelet therapy.

Tropoelastin inhibits vascular calcification via 67-kDa elastin binding protein in cultured bovine aortic smooth muscle cells.

In cases of vascular calcification, the expression of tropoelastin is down-regulated, which most likely decreases elastic fiber formation. However, the function of tropoelastin in vascular calcification remains unknown. We investigated whether tropoelastin affects the induction of vascular calcification. Calcification was induced using inorganic phosphate in cultured bovine aortic smooth muscle cells. The increase in tropoelastin due to the addition of recombinant bovine tropoelastin (ReBTE; 1 or 10 microg/ml) or beta-aminopropionitrile (25 microg/ml) significantly inhibited calcification at day 6, as assessed by the o-cresolphthalein complexone method. The addition of an elastin-derived peptide, VGVAPG peptide (0.1-1,000 nM), inhibited calcification at day 6 in a dose-dependent manner. In addition, these responses of beta-aminopropionitrile, ReBTE, and VGVAPG peptide were confirmed using von Kossa staining. To examine whether ReBTE inhibited calcium deposition via the elastin binding protein, lactose and elastin-specific antibody were used. The combination of lactose (20 mM) or this antibody (50 microg/ml) with ReBTE (10 microg/ml) attenuated the inhibition of calcification. These results suggest that increased tropoelastin inhibits vascular calcification in this model via the interaction between tropoelastin and elastin binding protein.