ABSTRACT
The academic, clinical and economic impacts of active approaches to wound care remain undetermined because wound healing occurs through a complex interaction of enzymatic cascades and a cellular module of interdependent components. Platelet-derived wound healing factors, which are released from the platelet alpa-granule, are currently recognized as the main element in wound healing process. This study is aimed at determining whether the human platelet supernatants including various growth factors would improve the wound healing process in vitro and in vivo studies. Platelet supernatants or platelet poor plasma was added to cultured skin fibroblasts and also applied on 8 mm diameter full thickness defects on rabbit ears(4.0-4.5 kg, New Zealand white rabbit). For the determination of cell growth, DNA and collagen synthesis were measured with [3H]-thymidine and [3H]-proline incorporation. For the determination of wound healing, three full thickness defects were made on each rabbit ear and the subjects were divided into 3 groups: control group treated with normal saline(n = 10), platelet supernatants treated group(n = 10), platelet poor plasma treaed group(n = 10). Histologic sections crossing the center of the wound were obtained on the 7th day after the operation. The diameter of wound gap was subsequently measured with a calibrated lens micrometer and the area of new graulation was measured with an image analyzing system. The results were as follows: 1. The platelet supernatants group revealed a significant increment in the DNA and collagen synthesis as compared to that of the platelet poor plasma group(p< 0.05). DNA synthesis and collagen synthesis of cultured fibroblasts in the platelet poor plasma group were significantly increased as compared to the control groups(p< 0.05). 2. The wound diameters were significantly decreased in the platelet supernatants group and new granulation tissues recovered the wound intensively in the platelet supernatants group as well, as compared to the control or platelet poor plasma group(p< 0.05). These results suggested that the platelet supernatants increases proliferation and collagen synthesis of fibroblasts and virtually promotes the wound healing process. As platelet supernatants is safe and cost effective and can be obtained by a simple method, it may be clinically useful as a source of growth factors.
Subject(s)
Humans , Blood Platelets , Collagen , DNA , Ear , Fibroblasts , Granulation Tissue , Intercellular Signaling Peptides and Proteins , New Zealand , Plasma , Skin , Wound Healing , Wounds and InjuriesABSTRACT
The availability of a large number of chondrocytes is important for cartilage tissue engineering. Chondrocytes have been shown to be sensitive to the proliferative action of a wide variety of growth factors. Many of these growth factors have been isolated from platelets. In this study, we tested whether human platelet supernatants, as a supplement to basic medium, would support the proliferative and secretary activity of rabbit auricular chondrocytes in low- density monolayer culture. In 5% serum supplemented cultures, uptake of [H]-thymidine was increased in platelet supernatant-treated chondrocytes by 1.9-2.5 fold at 72 hours compared with controls. In serum free cultures, the ability of platelet supernatants to promote proliferative activity was decreased compared with serum supplemented cultures. In 5% serum supplemented cultures, glycosaminoglycan synthesis was increased in platelet supernatant-treated chondrocytes at 96 hours compared with controls. In serum supplemented cultures, seeding efficiency was increased in platelet supernatant-treated cultures by more than 3-fold compared with controls. These results indicate that platelet supernatant promotes proliferation and matrix synthesis of rabbit auricular chondrocytes. Platelet supernatants may be useful as a cheap autologous source of multiple growth factors to increase in vitro expansion of chondrocytes.
Subject(s)
Humans , Blood Platelets , Cartilage , Chondrocytes , Intercellular Signaling Peptides and Proteins , Tissue EngineeringABSTRACT
Craniofacial reconstructive procedures are frequently peformed with rigid fixation of the bone. During the period of active bone growth such manipulation may influence bone development. The purpose of this study was to determine the effects of metal plating of the mandible on the growth and morphology of the mandibulofacial skeleton. New Zealand white rabbits, 6 to7 weeks of age, were divided into 5 groups. They were designated as group I(nonoperated control, n=10), group II (rigid fixation of mandibular body after vertical osteotomy, n=10), group III(rigid fixation without osteotomy, n=10), group IV (interosseous wire fixation after osteotomy, n=10), and group V(rigid fixation and removal of plates and screws 4 weeks after osteotomy, n=7). Rabbits were sacrificed 12 weeks after operation and dry skull preparations were grossly measured and analyzed by direct measurement and by dorsoventral skull x-rays. Measurements taken were length, thickness, angle, and area of the mandibulofacial skeleton. Three-dimensional CT was used for volumetric measurement of the mandible. The data wee compared between the operated and nonoperated sides and significant differences between groups were evaluated using the paired t-test, the ANOVA test, and Dunn's test. The following results were obtained: 1. The length of the whole mandible and the anterior mandibular segment was decreased in groups II and III, compared with group I(p>0.05). These results show growth restriction of the plated mandible regardless of osteotomy. 2. The maxillary alveolus of the operated side was more anteriorly placed in groups II and III, compared with group I (p>0.05). 3. The thickness of the operated mandibular body showed a significant increase in groups II and III, compared with group I(p>0.05). 4. The length of the zygomatic arch of the operated side in all the experimental groups showed a significant decrease, compared with group I(p>0.05). The angular divergence of the mandibular ramus from the sagittal midline of the skull was increased in the operated side of groups II and III, compared with the nonoperated side (p>0.05). 5. Volume measurements of the mandible in groups II and III showed a significant reduction of the volume on the operated sides in the anterior mandibular segment, compared with group I(p>0.05). The volume of the operated mandibular body showed a significant increase in groups II and III, compared with group I(p>0.05). All gruops showed no significant difference in total hemiman dibular volume of the operated side compared with the nonoperated side. These results show that rigid fixation of mandibular fractures during the growth period causes a more severe growth restriction than either osteotomy or interosseous wiring.
Subject(s)
Rabbits , Bone Development , Electroplating , Mandible , Mandibular Fractures , Osteotomy , Skeleton , Skull , ZygomaABSTRACT
It remains a problem that successful revascularization and reperfusion after ischemia are associated with high systemic complication rates and severe local tissue injuries. With prolonged ischemia, there is damage to tissue from anoxia, but further injury may occur after reperfusion. The activation of leukocytes and endothelial cells during reperfusion causes neutrophil adhesion in capillaries, resulting in plugging and further ischemia, Alternativety, neutrophil adhesion to endothelium leads to the migration of neutrophil with local edema formation, hemorrhage and thrombosis. Some chemotactic and activating factors are needed to propel neutrophils to the site of local inflammation. The chief cytikines that induce a pro-adhesive state in endothelium are tumor necrosis factor-alpha(TNF-alpha), interleukin-1 beta(IL-1 beta) and endotoxin or lipopolysaccharide(LPS). Similarly, TNF-alpha,and to a lesser extent interleukin-8(IL-8), is the important stimulus that acts on neutrophils and other leukocytes to alter their adhesion. The purpose of this study was to evaluate the pathogenetic role of IL-8 after perfusion with CDl8 monoclonal antibody(CDl8 mAb), the blocking antibody of neutrophil adherence, on reperfusion injury in rat epigastric island skin flap. A 6 X 3 cm-sized island skin flap was made on the abdomen. The epigastric pedicle was occluded for six hours with ambient temperature. Fifteen minutes before reperfusion, the flap was perfused with saline and CDl8 mAb(1 mg/kg). For evaluation of IL-8 levels, tissue fluid and serum were obtained at 4, 8, 12 and 24 hours after reperfusion. IL-8 concentrations of the CDl8 mAb group in the tissue fluid were significantly decreased at 8, 12 and 24 hours compared to the control group(P > 0.01), but the difference between the two groups was not significant at 4 hours after reperfusion IL-8 concentrations of the CDl8 mAb group in the serum were significantly decreased over time compared to the control group(P > 0.05, p > 0.01). Form the above results, we concluded that blocking neutrophil adherence using CD18 mAb within the peak level of IL-8 at 4 hours after reperfusion may be a better method of reducing reperfusion injury to the island skin flap.