Combined use of platelet-rich plasma and adipose tissue-derived mesenchymal stem cells shows a synergistic effect in experimental spinal cord injury.

Spinal cord injury (SCI) as a crippling disability causes tissue degeneration via neuron loss and fiber disruption. Some researchers have tried to reverse or minimize these changes. Platelet-rich plasma (PRP) is a biological product derived from peripheral blood containing a variety of growth factors. PRP has been extensively used in regenerative medicine. On the other hand, via secreting neuroprotective growth factors, mesenchymal stem cells (MSCs) have shown a promising potential in repairing central nervous system deficits. This study investigated the therapeutic effect of the combined use of MSCs and PRP in a rat model of SCI. We used real time-PCR method for evaluation of Bcl-2, Bax and caspase 3 expressions, TUNEL test for apoptotic cell death assessment, and neurofilament NF200 immunohistochemistry for examination of axonal regeneration. The results showed that co-treatment with MSCs and PRP efficiently alleviated the evaluated categories. Significant differences were observed in expression of Bcl-2 and caspase3, but not Bax, apoptotic index and the number of NF200 positive axons (for all P ≤ 0.01) between co-treatment animals compared with those treated with only MSCs or PRP. In conclusion, this study showed that combination of MSCs and PRP synergistically promotes their therapeutic effects in the SCI.

Adipose tissue-derived mesenchymal stem cells and keratinocytes co-culture on gelatin/chitosan/ß-glycerol phosphate nanoscaffold in skin regeneration.

Using cell-based engineered skin is an emerging strategy for treating difficult-to-heal wounds. To date, much endeavor has been devoted to the fabrication of appropriate scaffolds with suitable biomechanical properties to support cell viability and growth in the microenvironment of a wound. The aim of this research was to assess the impact of adipose tissue-derived mesenchymal stem cells (AD-MSCs) and keratinocytes on gelatin/chitosan/ß-glycerol phosphate (GCGP) nanoscaffold in full-thickness excisional skin wound healing of rats. For this purpose, AD-MSCs and keratinocytes were isolated from rats and GCGP nanoscaffolds were electrospun. Through an in vivo study, the percentage of wound closure was assessed on days 7, 14, and 21 after wound induction. Samples were taken from the wound sites in order to evaluate the density of collagen fibers and vessels at 7 and 14 days. Moreover, sampling was done on days 7 and 14 from wound sites to assess the density of collagen fibers and vessels. The wound closure rate was significantly increased in the keratinocytes-AD-MSCs-scaffold (KMS) group compared with other groups. The expressions of vascular endothelial growth factor, collagen type 1, and CD34 were also significantly higher in the KMS group compared with the other groups. These results suggest that the combination of AD-MSCs and keratinocytes seeded onto GCGP nanoscaffold provides a promising treatment for wound healing.

Determination of imipenem efflux-mediated resistance in Acinetobacter spp., using an efflux pump inhibitor.

BACKGROUND AND OBJECTIVES: In recent years, reports of Acinetobacter strains resistant to all known antibiotics have caused a great concern in medical communities. Overexpression of efflux pumps is one of the major causes of resistance in bacteria. The aim of this study was to investigate the role of efflux pumps in conferring resistance to imipenem in clinically important Acinetobacter spp; Acinetobacter baumannii and Acinetobacter lwoffii. MATERIALS AND METHODS: A total number of 46 clinical Acinetobacter isolates, including 33 A. baumannii and 13 A. lwoffii isolates, previously collected from Shahid Kamyab and Ghaem hospitals of Mashhad, Iran were used in this study. Imipenem susceptibility testing was carried out by the disc diffusion method. Imipenem minimum inhibitory concentration (MIC) for resistant Acinetobacter isolates were determined both in the presence and absence of the efflux pumps inhibitor, carbonyl cyanide 3-chlorophenylhydrazone (CCCP). RESULTS: Resistance to imipenem was observed in 38 isolates including 30 A. baumannii and 8 A. lwoffii isolates. Experiments in the presence of CCCP showed a 2 to 16384 fold reduction in imipenem MICs in 14 A. baumannii and 2 A. lwoffii isolates. CONCLUSION: The results obtained showed high levels of resistance to imipenem and contribution of efflux pumps in conferring resistance in both Acinetobacter species in this study. Moreover, imipenem efflux mediated resistance highlights the importance of this mechanism not only in A. baumannii but also in non-baumannii Acinetobacter Spp. which have been neglected in antibiotic resistance studies.

Platelet rich plasma: Effective treatment for repairing of spinal cord injury in rat.

OBJECTIVE: The aim of the present study was to evaluate the effect of PRP on the repair of spinal cord injury in rat model. MATERIAL AND METHODS: Rats were randomly divided into three groups with six rats in each group. Then, spinal cord injury was performed under general anesthesia using "weight dropping" method. Control group included rats receiving normal saline, group two received PRP 1 week after injury; group three received PRP 24 h after injury. The motor function was assessed weekly using the Basso, Beattie, and Bresnahan (BBB) locomotor rating scale. Anterograde tracing was performed for evaluation of axon regeneration. RESULT: Motor recovery was significantly better in the rats treated with PRP 24 h after injury than the control group. In the rats treated with PRP 1 week after injury and rats treated with PRP 24 h after injury, the average numbers of BDA-labeled axons were statistically different from the control group. CONCLUSION: Our experimental study demonstrated positive effects of platelet rich plasma on nerve regeneration after spinal cord injury.

Hybrid chitosan-ß-glycerol phosphate-gelatin nano-/micro fibrous scaffolds with suitable mechanical and biological properties for tissue engineering.

Scaffold-based tissue engineering is considered as a promising approach in the regenerative medicine. Graft instability of collagen, by causing poor mechanical properties and rapid degradation, and their hard handling remains major challenges to be addressed. In this research, a composite structured nano-/microfibrous scaffold, made from a mixture of chitosan-ß-glycerol phosphate-gelatin (chitosan-GP-gelatin) using a standard electrospinning set-up was developed. Gelatin-acid acetic and chitosan ß-glycerol phosphate-HCL solutions were prepared at ratios of 30/70, 50/50, 70/30 (w/w) and their mechanical and biological properties were engineered. Furthermore, the pore structure of the fabricated nanofibrous scaffolds was investigated and predicted using a theoretical model. Higher gelatin concentrations in the polymer blend resulted in significant increase in mean pore size and its distribution. Interaction between the scaffold and the contained cells was also monitored and compared in the test and control groups. Scaffolds with higher chitosan concentrations showed higher rate of cell attachment with better proliferation property, compared with gelatin-only scaffolds. The fabricated scaffolds, unlike many other natural polymers, also exhibit non-toxic and biodegradable properties in the grafted tissues. In conclusion, the data clearly showed that the fabricated biomaterial is a biologically compatible scaffold with potential to serve as a proper platform for retaining the cultured cells for further application in cell-based tissue engineering, especially in wound healing practices. These results suggested the potential of using mesoporous composite chitosan-GP-gelatin fibrous scaffolds for engineering three-dimensional tissues with different inherent cell characteristics.