fibrin and Contracture

A delayed full-thickness wound-healing model was developed and used for examining the capacity of adipose-derived stem cells (ASCs), either alone or in platelet-rich fibrin gels, to promote healing.. Four pigs received electron beam radiation to the dorsal skin surface. Five weeks after radiation, subcutaneous fat was harvested from nonirradiated areas and processed to yield ASCs. Two weeks later, 28 to 30 full-thickness 1.5-cm(2) wounds were made in irradiated and nonirradiated skin. Wounds were treated with either saline solution, ASCs in saline solution, platelet-rich plasma (PRP) fibrin gel, ASCs in PRP, or non-autologous green fluorescence protein-labeled ASCs.. The single radiation dose produced a significant loss of dermal microvasculature density (75%) by 7 weeks. There was a significant difference in the rate of healing between irradiated and nonirradiated skin treated with saline solution. The ASCs in PRP-treated wounds exhibited a significant 11.2% improvement in wound healing compared with saline solution. Enhancement was dependent on the combination of ASCs and PRP, because neither ASCs nor PRP alone had an effect.. We have created a model that simulates the clinically relevant late radiation effects of delayed wound healing. Using this model, we showed that a combination of ASCs and PRP improves the healing rates of perfusion-depleted tissues, possibly through enhancing local levels of growth factors.

Topics: Adipocytes; Animals; Contracture; Female; Fibrin; Microvessels; Models, Animal; Platelet-Rich Plasma; Radiation Injuries, Experimental; Radiodermatitis; Skin; Sodium Chloride; Stem Cell Transplantation; Swine; Wound Healing

Capsular contracture remains one of the most common complications involving aesthetic and reconstructive breast surgery; however, its cause, prevention, and treatment remain to be fully elucidated. Presently, there is no accurate and reproducible pathologic in vitro or in vivo model examining capsular contracture. The purpose of this study was to establish an effective pathologic capsular contracture animal model that mimics the formation of capsular contracture response in humans.. New Zealand White rabbits (n = 32) were subdivided into experimental (n = 16) and control groups (n = 16). Each subgroup underwent placement of smooth saline mini implants (30 cc) beneath the panniculus carnosus in the dorsal region of the back. In addition, the experimental group underwent instillation of fibrin glue into the implant pocket as a capsular contracture-inducing agent. Rabbits were euthanized from 2 to 8 weeks after the procedure. Before the animals were euthanized, each implant was serially inflated with saline and a pressure-volume curve was developed using a Stryker device to assess the degree of contracture. Representative capsule samples were collected and histologically examined. Normal and contracted human capsular tissue samples were also collected from patients undergoing breast implant revision and replacement procedures. Tissue samples were assessed histologically.. Pressure-volume curves demonstrated a statistically significantly increased intracapsular pressure in the experimental group compared with the control group. The experimental subgroup had thicker, less transparent capsules than the control group. Histologic evaluation of the rabbit capsule was similar to that of the human capsule for the control and experimental subgroups.. The authors conclude that pathologic capsular contracture can be reliably induced in the rabbit. This animal model provides the framework for future investigations testing the effects of various systemic or local agents on reduction of capsular contracture.

Topics: Animals; Breast Implantation; Breast Implants; Contracture; Disease Models, Animal; Female; Fibrin; Pressure; Rabbits

Burn wounds are characterised by central necrosis surrounded by an area of stasis with compromised perfusion. Secondary aggravation of the burn wound due to ischaemia in the zone of stasis can also result in necrosis. This study aims to improve circulation in the zone of stasis by reducing microthrombus formation and thereby to reduce secondary aggravation.. Recombinant nematode anticoagulant protein (rNAPc2) was administered to Wistar rats at 3 or 30 microg/kg as a single or daily dose. A comb pattern burn was induced on the dorsum of these rats and its evolution monitored by serial photography, planimetry, laser doppler flowmetry and immunohistochemistry.. In the 30 microg/kg daily group, extension of the burn wound was curbed, limiting the burn area to 1.99+/-0.67 cm(2) on day 28, compared to 3.51+/-0.37 cm(2) in the control group (p=0.015). Laser doppler evaluation showed a significant (p<0.001) increase in circulation in the first day post-burn. Significantly less (p<0.001) microvascular fibrin formation was observed by immunohistochemistry.. Anticoagulation with rNAPc2 improved perfusion of the burn wound. The resultant reduction in the area of the burn led to earlier healing and less scar contracture.

Topics: Animals; Anticoagulants; Burns; Cicatrix; Contracture; Fibrin; Flow Cytometry; Helminth Proteins; Male; Random Allocation; Rats; Rats, Wistar; Recombinant Proteins; Regional Blood Flow