fibrin and Wounds--Penetrating

Since its conceptualization in the 1980s, the provisional matrix has often been characterized as a simple fibrin-containing scaffold for wound healing that supports the nascent blood clot and is functionally distinct from the basement membrane. However subsequent advances have shown that this matrix is far from passive, with distinct compositional differences as the wound matures, and providing an active role for wound remodeling. Here we review the stages of this matrix, provide an update on the state of our understanding of provisional matrix, and present some of the outstanding issues related to the provisional matrix, its components, and their assembly and use in vivo.

Topics: Animals; Basement Membrane; Blood Platelets; Collagen; Extracellular Matrix; Fibrin; Fibroblasts; Fibronectins; Gene Expression; History, 20th Century; History, 21st Century; Humans; Proteoglycans; Signal Transduction; Skin; Wound Healing; Wounds, Penetrating

The in vivo formation of hemostatic plugs was studied in humans in skin wounds made using the template bleeding procedure of Mielke (34). The wounds were excised by punch biopsy 10 seconds, 30 seconds, 2 minutes, and 3 minutes after they were made. The wounds were V-shaped and approximately 0.4 mm. deep. Within 30 seconds small hemostatic plugs were observed at the end of transected vessels. The plugs grew in size in the subsequent minutes and became impermeable. The platelets degranulated and formed pseudopods which became strongly interdigitated. The platelets at the periphery of the plugs showed discontinuities of the membranes. Cytoplasmic matrix and cell organelles had disappeared in many of these peripheral cells. Small fibrin fibers were already found at 30 seconds, mostly along the margins of the wounds and also at the periphery of the hemostatic plugs. Fibrin was absent from the center of the plugs and from the lumen of transected vessels. When part of a plug was extending into the vessel lumen, the platelets inside the vessel were less degranulated and less interdigitated than the rest of the plug. The effect of acetysalicylic acid (ASA) was studied in wounds before and 2.5 hours after ingestion of 2 gm. of ASA. Wounds were excised by punch biopsy 3 or 10 minutes after they had been made. Platelets in ASA were less degranulated, had fewer pseudopods, and showed less interdigitation than platelets in control plugs. Ballooning and fibrin deposition were similar in control and ASA plugs. Pronounced differences between control and ASA plugs were observed in a subject who exhibited a considerably prolonged bleeding time after ASA. The ASA plugs were very large; many plugs had fused and in addition numerous small platelet clumps, most likely fragments from the plugs, were found in the superficial scab of the wound. It is postulated that ASA plugs are less stable due to decreased interdigitation. This allows more disruption of the plugs and rebleeding. Consequently, more platelets are needed and longer time is required for hemostasis to occur.

Topics: Adult; Aspirin; Blood Platelets; Cell Membrane; Fibrin; Hemostasis; Humans; Male; Microscopy, Electron; Pseudopodia; Skin; Time Factors; Wounds, Penetrating

Essentials Methods were developed to image the hemostatic response in mouse femoral arteries in real time. Penetrating injuries produced thrombi consisting primarily of platelets. Similar to arterioles, a core-shell architecture of platelet activation occurs in the femoral artery. Differences from arterioles included slower platelet activation and reduced thrombin dependence.. Background Intravital studies performed in the mouse microcirculation show that hemostatic thrombi formed after penetrating injuries develop a characteristic architecture in which a core of fully activated, densely packed platelets is overlaid with a shell of less activated platelets. Objective Large differences in hemodynamics and vessel wall biology distinguish arteries from arterioles. Here we asked whether these differences affect the hemostatic response and alter the impact of anticoagulants and antiplatelet agents. Methods Approaches previously developed for intravital imaging in the mouse microcirculation were adapted to the femoral artery, enabling real-time fluorescence imaging despite the markedly thicker vessel wall. Results Arterial thrombi initiated by penetrating injuries developed the core-and-shell architecture previously observed in the microcirculation. However, although platelet accumulation was greater in arterial thrombi, the kinetics of platelet activation were slower. Inhibiting platelet ADP P2Y

Topics: Adenosine Diphosphate; Animals; Anticoagulants; Arterioles; Blood Coagulation; Blood Platelets; Femoral Artery; Fibrin; Hemodynamics; Hemostasis; Intravital Microscopy; Mice; Mice, Inbred C57BL; Microcirculation; Platelet Activation; Platelet Aggregation Inhibitors; Signal Transduction; Thrombin; Thromboplastin; Thrombosis; Wounds, Penetrating

In this work, we have developed chitosan hydrogel/nanofibrin composite bandages (CFBs) and characterized using Fourier transform-infrared spectroscopy and scanning electron microscopy. The homogeneous distribution of nanofibrin in the prepared chitosan hydrogel matrix was confirmed by phosphotungstic acid-hematoxylin staining. The mechanical strength, swelling, biodegradation, porosity, whole-blood clotting, and platelet activation studies were carried out. In addition, the cell viability, cell attachment, and infiltration of the prepared CFBs were evaluated using human umbilical vein endothelial cells (HUVECs) and human dermal fibroblast (HDF) cells. It was found that the CFBs were microporous, flexible, biodegradable, and showed enhanced blood clotting and platelet activity compared to the one without nanofibrin. The prepared CFBs were capable of absorbing fluid and this was confirmed when immersed in phosphate buffered saline. Cell viability studies on HUVECs and HDF cells proved the nontoxic nature of the CFBs. Cell attachment and infiltration studies showed that the cells were found attached and proliferated on the CFBs. In vivo experiments were carried out in Sprague-Dawley rats and found that the wound healing occurred within 2 weeks when treated with CFBs than compared to the bare wound and wound treated with Kaltostat. The deposition of collagen was found to be more on CFB-treated wounds compared to the control. The above results proved the use of these CFBs as an ideal candidate for skin tissue regeneration and wound healing.

Topics: Animals; Bandages; Chitosan; Equipment Design; Equipment Failure Analysis; Fibrin; Hydrogels; Male; Materials Testing; Miniaturization; Nanoparticles; Porosity; Rats; Rats, Sprague-Dawley; Regeneration; Skin; Skin, Artificial; Treatment Outcome; Wound Healing; Wounds, Penetrating

Cutaneous wound contraction and epithelialization act collaboratively to minimize the exposed wound surface. However excessive wound contraction is undesirable due to the resultant disfigurement and scarring. Fibrin clot has greater stiffness than surrounding tissue and mechanical strain further enhances its stiffness. On the contrary, skin exhibits diminished stiffness when affected by high strain rates. Therefore during early stages of wound healing, the contractile wound border is confronted by fibrin clot forming a high strain region in the interface of contractile tissue and fibrin clot--which is evidenced by computer simulation. Due to the stress relaxation property of skin, the contractile strain is partly neutralized. Meanwhile, gradually the stiffness of fibrin clot decreases which is followed by another cycle of wound contraction. This cyclic pattern of contraction resembles the movement of a stone over water or "skipping stone". The stone bounces repeatedly when thrown across the surface of water with reduction of jumping altitude with each bounce till the stone stops completely. This hypothesis is further supported by the observed initial delay in wound contraction and the chronological correlation of enhanced wound contraction with loss of superficial eschar and substitution of fibrin clot with granulation tissue. Also there is evidence that fibrin inhibits fibroblast-mediated contraction of collagen. Furthermore, modest increase in wound contraction rate in fibrinogen deficient mice and fibrin-mediated diminished wound contraction are agreement with the proposed hypothesis.

Topics: Blood Coagulation; Blood Platelets; Cicatrix; Fibrin; Humans; Models, Cardiovascular; Skin; Wound Healing; Wounds, Penetrating

Fibrin glue (FG) is an effective hemostatic agent applied topically to the spleen. In this study, FG was found to be an effective hemostatic agent when applied topically in standardized wounds of the canine liver, spleen, and pancreas. It was markedly more effective, however, when injected intraparenchymally. In a case of severe blunt trauma in a patient with acute alcoholic hepatitis, intraparenchymal FG was lifesaving. Fibrin glue is a useful adjunct in the management of trauma to all the abdominal solid viscera. Intraparenchymal injection is the preferred mode of FG application.

Topics: Administration, Topical; Adult; Animals; Aprotinin; Dogs; Drug Combinations; Factor XIII; Fibrin; Fibrin Tissue Adhesive; Fibrinogen; Hemostasis, Surgical; Humans; Injections; Liver; Male; Pancreas; Spleen; Thrombin; Tissue Adhesives; Wounds, Penetrating

A method for studying wound healing in humans is described. The technique is based on the production of a standard subcutaneous injury during implantation of a retrievable sponge. The injury is produced by introducing a small device (PVA implant) which consists of a 5.7-cm piece of perforated silicone tubing containing two pieces of polyvinyl alcohol sponge. The sponge provides a site for attracting inflammatory cells with subsequent fibroblast infiltration. The sterile PVA implant is inserted subcutaneously in the upper arm by means of a 12-gauge needle and remains there for 14 days. Upon removal, one sponge has hydroxyproline deposition quantitated using a high-performance liquid chromatography technique. The other sponge may be processed for light and electron microscopy or specialty staining. Other collagen determinations such as percentage neutral salt-soluble collagen are also possible. Using the PVA implant has made it possible to follow the kinetics of collagen deposition in the rat. There was a marked increase in collagen accumulation from Day 2 (0.89 nmole/mg sponge) to Day 14 (18 nmole/mg sponge) in the rat. Collagen deposition was also measured in human control subjects (5.07 nmole/mg sponge, n = 12) and compared to trauma patients (2.04 nmole/mg sponge, n = 5). Histologic staining showing fibroblast infiltration and collagen deposition correlated well with the biochemical findings. This implant, coupled with recent HPLC technology, provides a safe, acceptable technique to study human wound healing parameters and overcomes many of the limitations of previous methods.

Topics: Adult; Animals; Collagen; Connective Tissue; Fibrin; Fibroblasts; Humans; Hydroxyproline; Male; Middle Aged; Polyvinyl Alcohol; Prostheses and Implants; Rats; Rats, Inbred Strains; Silicones; Skin; Wound Healing; Wounds, Penetrating

Haemostatic plug formation in four patients with severe haemophilia A (VIII:C less than 1%) was studied in skin biopsies taken at 3, 10 and 30 min and 2 h after a template bleeding time wound had been made. The primary haemostatic plug showed relatively minor changes, consisting of a delay in platelet degranulation and interdigitation. Some platelet aggregates not attached to vessels were encountered in the wound. Subsequently the primary haemostatic plug changed into a firm stable degranulated mass of interdigitated platelets. The major abnormality occurred during the fibrinous transformation. At 2 h many haemostatic plugs consisted of a thin peripheral layer of fibrin and platelet remnants around a central area containing red and white blood cells with a varying amount of plasma and only relatively few fibrin fibres. These observations suggest that fibrin formation in the periphery of the plug is less dependent of factor VIII than in central areas. The lack of fibrin formation in the centre of the plug compensating for the platelet lysis at 2 h may have caused the central erosion of the plug.

Topics: Adult; Bleeding Time; Blood Platelets; Fibrin; Hemophilia A; Hemostasis; Humans; Microscopy, Electron; Middle Aged; Skin; Time Factors; Wounds, Penetrating