Stimulation of wound healing by positively charged dextran beads depends upon clustering of beads and cells in close proximity to the wound

We have previously shown that positively charged dextran (DEAE A25) increases wound breaking strength in linear incisions in rats and nonhuman primates at days 10-14 postwounding. In this article, we examined the cellular responses to different types of charged dextran beads (DEAE A50 and Cytodex-1) in culture studies and in rat incisional wounds. We show that Cytodex 1 and DEAE A50 beads also increased wound breaking strength in a rat linear incisional model. However, the increase was approximately 30-40% less than that observed in wounds treated with DEAE A25 beads. The main distinction between the three types of beads was the presence of bead clusters observed in tissue sections. Wounds treated with DEAE A25 beads formed distinct clusters while both Cytodex 1 and DEAE A50 beads clustered to a lesser extent or failed to cluster at all. We propose that the different types of charged dextran beads improve healing by promoting cell adhesion and encouraging proliferation in close proximity to the wound. We also hypothesize that the 30-40% improvement in wound breaking strength seen with DEAE A25 beads compared to other types of charged dextran beads (DEAE A50 and Cytodex-1) originates from the unique characteristic of DEAE A25 beads in forming cell-bead aggregates adjacent to the wounded area. This clustering, in turn, affects the distribution of cells infiltrating the wounded area (such as macrophages) during the healing process and, as a consequence, alters the distribution of matrix molecules and growth factors secreted by these cells.

Acceleration of wound healing with topically applied deoxyribonucleosides

HYPOTHESIS

We hypothesized that a topical mixture of purified deoxyribonucleosides would accelerate wound healing in an open wound model.

DESIGN

Full-thickness 6-mm wounds were made on the ears of young adult rabbits. In some experiments, 2 of the 3 arteries in each ear were divided to induce wound ischemia.

INTERVENTIONS

An equiweight mixture containing all 4 of the major deoxyribonucleosides (deoxyadenosine, deoxycytidine, deoxyguanosine, and thymidine), designated PN105, or other subgroups of deoxyribonucleosides, or vehicle (saline) was applied to wounds on 1 ear every 2 days, with the other ear serving as a control.

MAIN OUTCOME MEASURES

Wound tissue was processed for histological examination 7 days after the initial wounding. Granulation tissue formation and epithelialization were measured in histological cross sections of wounds.

RESULTS

Treatment of wounds with PN105 resulted in a 191% increase in total new granulation tissue (P<.05) and a higher incidence of complete wound reepithelialization (67% vs 37%; P<.05) when compared with controls, and a similar increase under ischemic conditions on day 7. Wound ischemia markedly impairs healing; PN 105 treatment resulted in a 242% increase in the amount of new granulation tissue formed by day 7 in ischemic wounds, relative to the appropriate controls (P<.05). All 4 of the major deoxyribonucleosides were required for optimum activity; mixtures with 3 or 2 were less active or inactive.

CONCLUSIONS

Topically applied deoxyribonucleosides reproducibly accelerate wound healing in normal and ischemic wounds, and to a magnitude equivalent to that of recombinant growth factors such as platelet-derived growth factor, previously studied in this model. In view of their safety, availability, and efficacy, deoxyribonucleosides hold considerable promise for improving healing of chronic wounds.

Charged beads enhance cutaneous wound healing in rhesus non-human primates

Enhanced cutaneous wound healing by positively charged cross-linked diethylaminoethyl dextran beads (CLDD) was studied in a standardized incisional wound model in 20 adult and 20 geriatric Macaca mulatta (rhesus) partitioned equally over five time periods. Physiologic saline served as a control. Soft-tissue linear incisions were prepared between and 1 cm inferior to the scapulae. There were four incisions per rhesus; each incision was 1.5 cm long with 1 cm of undisturbed tissue between incisions, and both the experimental CLDD and physiologic saline treatments were administered to each rhesus. The incision treatments were either CLDD and soft-tissue closure with 4-0 BioSyn sutures or sterile physiologic saline and closure with 4-0 BioSyn sutures. The hypothesis was CLDD would enhance cutaneous wound repair. Verification of the hypothesis consisted of clinical examinations and histologic and tensiometric evaluations on biopsy specimens at 10 and 15 days, whereas 5-day and 2- and 4-month groups were assessed clinically and biopsy specimens were assessed histologically. The clinical course of healing for all groups was unremarkable. At 10 days, incisions in adult rhesus treated with CLDD had a 30-percent greater tensile strength compared with the physiologic saline-treated incisions (p = 0.01), whereas for geriatric rhesus, the CLDD treatment proved to be 15 percent greater in tensile strength compared with the physiologic saline cohort (p = 0.11). By day 15, incisions in adult rhesus were 26 percent stronger than the saline treatment group (p = 0.07), and the difference was 36 percent (p = 0.02) for the geriatric rhesus. From 5 through 15 days, histologic observations revealed a gradual decrease in quantity and integrity of CLDD, with no remnants of CLDD at either 2 or 4 months. Macrophages and multinucleated giant cells were localized in the dermis and were associated with the CLDD. These cells decreased commensurately with the decrease of CLDD beads. The data suggest that CLDD can enhance significantly the tensile properties of healing cutaneous wounds in both adult and geriatric rhesus. Moreover, if the wound healing is enhanced in geriatric patients, this finding may be clinically germane to conditions where wound healing is compromised, such as in diabetics and patients on steroids.

A novel protein expressed in mammalian cells undergoing apoptosis

Human and rodent cells undergoing apoptosis were observed to express high levels of a novel 45,000 M(r) protein. The protein, which we have termed apoptosis specific protein (ASP), was found in Burkitt lymphoma (BL) cells and in adenovirus-transformed human and rat embryo cells induced into apoptosis by a variety of stimuli, including serum deprivation, exposure to the Ca2+ ionophore, ionomycin, treatment with inhibitors of macromolecular synthesis (cycloheximide and actinomycin D), and cold shock. In BL cells treated with apoptotic stimuli, expression of the oncoprotein Bcl-2 was found to both protect from apoptosis and prevent expression of ASP. ASP was not detected either in viable cells or in cells dying passively by necrosis. Laser scanning confocal microscopy showed high levels of ASP in the cytoplasm of cells displaying the chromatin condensation and fragmentation patterns typical of apoptosis. Retention of ASP was observed even when DNA was no longer detectable, and two-color immunofluorescence staining indicated that the protein primarily colocalized with, but was clearly distinct from, non-muscle actin. These findings, together with the observation that biochemical extraction of ASP was only possible under conditions which caused solubilization of the cytoskeleton, leads us to conclude that ASP forms part of, or at least strongly associates with, a modified cytoskeleton unique to cells undergoing apoptosis. While elucidation of its function will require further work, ASP constitutes a powerful marker for the diagnosis and quantitation of apoptosis in vivo and in vitro.

The quaternary structure of the adenovirus 12 early region 1B 54K protein

The quaternary structure of the adenovirus early region 1B 54K protein has been examined under denaturing and nondenaturing conditions. In the presence of SDS the protein has a strong tendency to form disulfide-linked high-molecular-weight polymers. Under nondenaturing, but reducing, conditions the in vitro-translated 54K polypeptide forms oligomers (probably tetramers) of molecular weight approximately 2 x 10(5). After subcellular fractionation of Ad12 early region 1-transformed cells, the 54K E1B protein present in the cytoplasm had a molecular weight similar to that determined for the in vitro-translated material. However, two populations of the viral protein could be distinguished in the nucleus-one of a size similar to that seen in the cytoplasm and the other of appreciably higher molecular weight (approximately 2 x 10(6)). No difference in migration pattern was observed after treatment of the nuclear extract with DNase I or RNase. A proportion of the Ad12 E1B 54K protein in both the high- and the low-molecular-weight populations in the nucleus was found to form a complex with p53, and it is therefore concluded that the very high molecular weight derives from interaction with an, as yet, unidentified component.

Closure of a sternal defect with the rectus abdominis muscle after sacrifice of both internal mammary arteries

Infections of the median sternotomy incision are relatively uncommon. Successful treatment of this serious complication consists of adequate surgical debridement and obliteration of mediastinal dead space using the pectoralis major muscle, or the rectus abdominis muscle or both. The recent use of internal mammary artery grafts has created a new problem in closure of defects involving the lower one-third of the sternum. Under these circumstances the use of the rectus abdominis muscle is believed to be contraindicated. To date omental transposition remains the only alternative in therapy. A case of sternal dehiscence after coronary artery bypass surgery is described. Bilateral internal mammary artery grafts were used. A rectus abdominis flap based primarily on the eighth anterior intercostal perforator was transposed into the defect. The wound healed uneventfully after initial loss of a 3-cm portion of the skin graft. Success of this flap based on intercostal perforators is postulated to be secondary to a "delay" phenomenon related to prior division of the dominant blood supply.

Carcinoma in chronic pressure sores: a fulminant disease process

Four cases of squamous cell carcinoma arising from chronic pressure sores in paraplegic and tetraplegic patients are presented and the literature reviewed. These pressure-sore carcinomas are characterized by a shorter latency period and a fulminant clinical course with a very high metastatic rate. Very aggressive treatment including even hemicorporectomy must be considered if a cure is to be achieved.

Adult epiglottitis

Seventy-five patient-episodes of adult epiglottitis were analyzed retrospectively. Six tracheotomies were performed, and no deaths occurred. In a large subset of patients, viral pathogenesis was suggested by benign clinical courses that included normal or mildly elevated temperatures and minimally elevated leukocyte counts with relative lymphocytosis. Hospitalization may not be indicated for adults with epiglottitis of viral etiology as it is for patients with signs of bacterial infections.