Immunologic function in the elderly after injury--the neutrophil and innate immunity.

BACKGROUND: Aging is associated with a decline in immune function. This may contribute to decreased ability of an elderly patient to mount an appropriate innate inflammatory response when injured. This study examined elderly trauma patients to determine whether there was a difference in neutrophil response to injury when compared with controls. METHODS: This prospective, observational, cohort study compared neutrophil function in 24 injured elderly (older than 65 years) patients admitted to our trauma center to control groups of noninjured individuals (11 elderly and 17 young). Blood samples were also taken from the injured elderly group within 48 hours of trauma and subsequently at two periods during their hospital stay. A single blood sample was obtained from the noninjured control groups. Neutrophils were analyzed for CD18 expression, stimulated oxidative burst, apoptosis, and IL-10. Results were compared using one-way analysis of variance (alpha 0.05). This study was approved by the Institutional Review Board. RESULTS: Twenty-four injured elderly subjects were enrolled: mean injury severity score 15.3, average age 74.6 years, 92% survival, 100% blunt trauma. CD18 levels in the elderly injured subjects for all three time periods were significantly higher than both control groups. When evaluated between controls, CD18 for the noninjured elderly (NIE) was also significantly higher than the noninjured young (NIY). The neutrophil stimulated oxidative burst in the injured elderly subjects at time periods 1, 2, and 3 was not significantly different from the NIY controls. However, the injured elderly had a significantly higher oxidative burst at time period 3 than the NIE controls. Apoptosis in the injured elderly subjects was significantly lower in all three time periods than the NIY. There was no difference in apoptosis between the injured elderly subjects when compared with the NIE controls. There was no significant difference in IL-10 expression among groups. CONCLUSION: Injury results in differences in innate immune function in the elderly when compared with controls. The clinical significance of this is uncertain and warrants further investigation.

Fluorinated methacrylamide chitosan hydrogel dressings enhance healing in an acute porcine wound model.

Wound healing involves multiple interrelated processes required to lead to successful healing outcomes. Phagocytosis, inflammation, cell proliferation, angiogenesis, energy production, and collagen synthesis are all directly or indirectly dependent on oxygen. Along with other critical factors, such as nutrition and comorbidities, availability of oxygen is a key determinant of healing success. Previously, we have presented a novel oxygenated hydrogel material that can be made into dressings for continuous localized oxygen delivery to wounds. In this study, an acute porcine wound model was used to test the healing benefits of these oxygenated MACF (MACF + O2) hydrogel dressings compared to controls, which included commercial Derma-GelTM hydrogel dressings. Wound closure and histological analyses were performed to assess re-epithelialization, collagen synthesis, angiogenesis, and keratinocyte maturation. Results from these assays revealed that wounds treated with MACF + O2 hydrogel dressings closed faster as compared to Derma-Gel (p<0.05). Targeted metabolomics via liquid chromatography separation and mass spectrometric detection (LC-MS/MS) and a biochemical assay determined the concentration of hydroxyproline in wound samples at days 14 and 21, showing that MACF + O2 hydrogel dressings improved wound healing via an upregulated collagen synthesis pathway as compared to Derma-Gel (p<0.05). Histological evidence showed that MACF + O2 hydrogel dressings improve new blood vessel formation and keratinocyte maturation over all other treatments.

Current challenges in dedifferentiated fat cells research.

Dedifferentiated fat cells show great promises as a novel cell source for stem cell research. It has many advantages when used for cell-based therapeutics including abundance, pluripotency, and safety. However, there are many obstacles researchers need to overcome to make the next big move in DFAT cells research. In this review, we summarize the current main challenges in DFAT cells research including cell culture purity, phenotypic properties, and dedifferentiation mechanisms. The common methods to produce DFAT cells as well as the cell purity issue during DFAT cell production have been introduced. Current approaches to improve DFAT cell purity have been discussed. The phenotypic profile of DFAT cells have been listed and compared with other stem cells. Further studies on elucidating the underlying dedifferentiation mechanisms will dramatically advance DFAT cell research.

Improving delivery of hydrophobic drugs from hydrogels through cyclodextrins.

A simple and effective technique of improving delivery of hydrophobic drugs from swellable systems is presented. Conventional methods of drug loading in hydrogel systems are limited by the characteristics of the pharmacological agent. The approach we present uses complexants to modulate drug release. Crosslinked poly(ethylene glycol) (PEG) hydrogels were synthesized, characterized, and used for vascular applications. The release of cyclosporine (CyA) from PEG hydrogels is significantly altered by the sterilization techniques. It was hypothesized that the release of CyA from PEG hydrogels can be modulated by using complexants. A cyclodextrin-CyA complex solution was prepared and used for drug loading. The sterilized PEG hydrogels that were loaded using the cyclodextrin-CyA complex solution had favorable release characteristics compared with the release from PEG hydrogels that were loaded using the conventional technique. Hence, drug release from swellable systems can be tailored by the application of this strategy.

Polymeric sustained local drug delivery system for the prevention of vascular intimal hyperplasia.

Anastomotic intimal hyperplasia (IH) is a major cause of both autologous vein and synthetic vascular graft failure. We have previously published data suggesting that cyclosporin may reduce the development of IH in a canine model. However, systemic administration of cyclosporin could create serious adverse effects. Therefore, it is our long-term goal to test the hypothesis that the controlled local release of cyclosporin from a polymeric vascular wrap will prevent the development of IH. To test this hypothesis, we developed a controlled release vascular wrap (sheet/ring) using a poly(ethylene glycol) (PEG) hydrogel. Sterilization of the polymers was performed using the ethylene oxide and hydrogen peroxide sterilization methods. It was found that except for one combination (8000 molecular weight and 1:1 crosslinking ratio), the differences in the swelling ratios for the sterilized and unsterilized hydrogels were not statistically significant. Release studies from unsterilized and ethylene oxide-sterilized PEG hydrogels were conducted. It was found that release lasted for approximately 50 h for sterilized as well as unsterilized PEG hydrogels. Acute animal studies, to test the deployment of both the polymeric sheets and rings to the adventitial surface of native arteries and veins, were completed successfully.

Endoluminal reconstruction of the canine common biliary duct.

PURPOSE: Extrahepatic biliary duct injuries such as transections, stenoses, and biliary leaks are well-known complications of upper abdominal surgeries. The popularization of laparoscopic cholecystectomies in the early 1990's resulted in an increase in the numbers of these reported injuries. The surgical repair of these injuries may be challenging. In this feasibility study, we were presented with the opportunity to evaluate a novel polytetrafluoroethylene (PTFE) covered stent graft that could be useful in common bile duct reconstructions. The long-term goal of this research is to offer the surgeon a new technique for reconstructing the biliary duct or repairing biliary strictures.John G. Zografakis MD, was the first place winner in the Basic Sciences Resident Competition at the Ohio American College of Surgeons meeting. METHODS: Seven dogs were originally enrolled in the study. After general endotracheal anesthesia and open cholecystectomy, the common bile duct was identified in each dog. A guide wire was then passed through the neck of the cystic duct, anterograde into the common bile duct, through the Ampulla of Vater and into the duodenum. A stent graft delivery system was placed over the wire, and the covered stent graft was deployed within the lumen of the common bile duct. Study outcomes included graft patency and assessment of the bio-incorporation of the graft and the effectiveness of the graft to drain the biliary system as determined by liver enzyme tests. RESULTS: Three implants were harvested at 1 month, and 2 grafts were harvested each at 3 months and 6 months postoperatively. All of the stent grafts were patent. Liver enzyme tests revealed that all dogs had increased serum levels of alkaline phosphatase, alanine aminotransferase (ALT) serum glutamate pyruvate transaminase (SGPT) and aspartate aminotransferase (AST) serum glutamic oxaloacetic transaminase (SGOT). Four dogs had increased total bilirubin. These increases were all measured in the immediate postoperative period. Peak levels for each measure were reached between 4 and 10 days and then gradually trended toward baselines by 1 month postoperatively. We did not observe meaningful changes in serum albumin or total protein. One dog suffered a tear in the common bile duct due to balloon overinflation. This tear was suture repaired when the graft was implanted. However, bile leakage was found when the graft was harvested at 1 month postoperatively. There appeared to be minimal bio-incorporation of the stent-grafts into the biliary duct wall, and there was no pronounced inflammatory response found in the duct wall or surrounding tissues. CONCLUSIONS: We are encouraged by these early results. Additional studies are planned to evaluate a self-expanding PTFE covered stent graft and a percutaneous delivery system.

Effects of sterilization on poly(ethylene glycol) hydrogels.

The past few decades have witnessed a dramatic increase in the development of polymeric biomaterials. These biomaterials have to undergo a sterilization procedure before implantation. However, many sterilization procedures have been shown to profoundly affect polymer properties. Poly(ethylene glycol) hydrogels have gained increasing importance in the controlled delivery of therapeutics and in tissue engineering. We evaluated the effect of ethylene oxide (EtO), hydrogen peroxide (H(2)O(2)), and gamma sterilization of poly(ethylene glycol) hydrogels on properties relevant to controlled drug delivery and tissue engineering. We observed that the release of cyclosporine (CyA) (an immunosuppressive drug that is effective in combating tissue rejection following organ transplantation) was significantly affected by the type of sterilization. However, that was not the case with rhodamine B, a dye. Hence, the drug release characteristics were observed to be dependent not only on the sterilization procedure but also on the type of agent that needs to be delivered. In addition, differences in the swelling ratios for the sterilized and unsterilized hydrogels were statistically significant for 1:1 crosslinked hydrogels derived from the 8000 MW polymer. Significant differences were also observed for gamma sterilization for 1:1 crosslinked hydrogels derived from the 3350 MW polymer and also the 2:1 crosslinked hydrogels derived from the 8000 MW polymer. Atomic force microscopy (AFM) studies revealed that the roughness parameter for the unsterilized and EtO-sterilized PEG hydrogels remained similar. However, a statistically significant reduction of the roughness parameter was observed for the H(2)O(2) and gamma-sterilized samples. Electron spin resonance (ESR) studies on the unsterilized and the sterilized samples revealed the presence of the peroxy and the triphenyl methyl carbon radical in the samples. The gamma and the H(2)O(2)-sterilized samples were observed to have a much higher concentration of the radical pecies when compared with the EtO and the unsterilized samples.