Use of poly(DL-lactide-ε-caprolactone) membranes and mesenchymal stem cells from the Wharton's jelly of the umbilical cord for promoting nerve regeneration in axonotmesis: in vitro and in vivo analysis

Cellular systems implanted into an injured nerve may produce growth factors or extracellular matrix molecules, modulate the inflammatory process and eventually improve nerve regeneration. In the present study, we evaluated the therapeutic value of human umbilical cord matrix MSCs (HMSCs) on rat sciatic nerve after axonotmesis injury associated to Vivosorb® membrane. During HMSCs expansion and differentiation in neuroglial-like cells, the culture medium was collected at 48, 72 and 96 h for nuclear magnetic resonance (NMR) analysis in order to evaluate the metabolic profile. To correlate the HMSCs ability to differentiate and survival capacity in the presence of the Vivosorb® membrane, the [Ca(2+)]i of undifferentiated HMSCs or neuroglial-differentiated HMSCs was determined by the epifluorescence technique using the Fura-2AM probe. The Vivosorb® membrane proved to be adequate and used as scaffold associated with undifferentiated HMSCs or neuroglial-differentiated HMSCs. In vivo testing was carried out in adult rats where a sciatic nerve axonotmesis injury was treated with undifferentiated HMSCs or neuroglial differentiated HMSCs with or without the Vivosorb® membrane. Motor and sensory functional recovery was evaluated throughout a healing period of 12 weeks using sciatic functional index (SFI), extensor postural thrust (EPT), and withdrawal reflex latency (WRL). Stereological analysis was carried out on regenerated nerve fibers. In vitro investigation showed the formation of typical neuroglial cells after differentiation, which were positively stained for the typical specific neuroglial markers such as the GFAP, the GAP-43 and NeuN. NMR showed clear evidence that HMSCs expansion is glycolysis-dependent but their differentiation requires the switch of the metabolic profile to oxidative metabolism. In vivo studies showed enhanced recovery of motor and sensory function in animals treated with transplanted undifferentiated and differentiated HMSCs that was accompanied by an increase in myelin sheath. Taken together, HMSC from the umbilical cord Wharton jelly might be useful for improving the clinical outcome after peripheral nerve lesion.

In vitro and in vivo chitosan membranes testing for peripheral nerve reconstruction

Tissue regeneration over a large defect with a subsequent satisfactory functional recovery still stands as a major problem in areas such as nerve regeneration or bone healing. The routine technique for the reconstruction of a nerve gap is the use of autologous nerve grafting, but still with severe complications. Over the last decades several attempts have been made to overcome this problem by using biomaterials as scaffolds for guided tissue regeneration. Despite the wide range of biomaterials available, functional recovery after a serious nerve injury is still far from acceptable. Prior to the use of a new biomaterial on healing tissues, an evaluation of the host's inflammatory response is mandatory. In this study, three chitosan membranes were tested in vitro and in vivo for later use as nerve guides for the reconstruction of peripheral nerves submitted to axonotmesis or neurotmesis lesions. Chitosan membranes, with different compositions, were tested in vitro, with a nerve growth factor cellular producing system, N1E-115 cell line, cultured over each of the three membranes and differentiated for 48h in the presence of 1.5% of DMSO. The intracellular calcium concentrations of the non-differentiated and of the 48h-differentiated cells cultured on the three types of the chitosan membranes were measured to determine the cell culture viability. In vivo, the chitosan membranes were implanted subcutaneously in a rat model, and histological evaluations were performed from material retrieved on weeks 1, 2, 4 and 8 after implantation. The three types of chitosan membranes were a viable substrate for the N1E-115 cell multiplication, survival and differentiation. Furthermore, the in vivo studies suggested that these chitosan membranes are promising candidates as a supporting material for tissue engineering applications on the peripheral nerve, possibly owing to their porous structure, their chemical modifications and high affinity to cellular systems.

In vitro and in vivo chitosan membranes testing for peripheral nerve reconstruction

Tissue regeneration over a large defect with a subsequent satisfactory functional recovery still stands as a major problem in areas such as nerve regeneration or bone healing. The routine technique for the reconstruction of a nerve gap is the use of autologous nerve grafting, but still with severe complications. Over the last decades several attempts have been made to overcome this problem by using biomaterials as scaffolds for guided tissue regeneration. Despite the wide range of biomaterials available, functional recovery after a serious nerve injury is still far from acceptable. Prior to the use of a new biomaterial on healing tissues, an evaluation of the host's inflammatory response is mandatory. In this study, three chitosan membranes were tested in vitro and in vivo for later use as nerve guides for the reconstruction of peripheral nerves submitted to axonotmesis or neurotmesis lesions. Chitosan membranes, with different compositions, were tested in vitro, with a nerve growth factor cellular producing system, N1E-115 cell line, cultured over each of the three membranes and differentiated for 48h in the presence of 1.5% of DMSO. The intracellular calcium concentrations of the non-differentiated and of the 48h-differentiated cells cultured on the three types of the chitosan membranes were measured to determine the cell culture viability. In vivo, the chitosan membranes were implanted subcutaneously in a rat model, and histological evaluations were performed from material retrieved on weeks 1, 2, 4 and 8 after implantation. The three types of chitosan membranes were a viable substrate for the N1E-115 cell multiplication, survival and differentiation. Furthermore, the in vivo studies suggested that these chitosan membranes are promising candidates as a supporting material for tissue engineering applications on the peripheral nerve, possibly owing to their porous structure, their chemical modifications and high affinity to cellular systems.

Neural cell transplantation effects on sciatic nerve regeneration after a standardized crush injury in the rat

The goal of the present study was to assess whether in vitro-differentiated N1E-115 cells supported by a collagen membrane would enhance rat sciatic nerve regeneration after a crush injury. To set up an appropriate experimental model for investigating the effects of neural cell transplantation, we have recently described the sequence of functional and morphologic changes occurring after a standardized sciatic nerve crush injury with a nonserrated clamp. Functional recovery was evaluated using the sciatic functional index, the static sciatic index, the extensor postural thrust, the withdrawal reflex latency, and ankle kinematics. In addition, histomorphometric analysis was carried out on regenerated nerve fibers by means of the 2D-disector method. Based on the results of the EPT and of some of the ankle locomotor kinematic parameters analyzed, the hypothesis that N1E-115 cells may enhance nerve regeneration is partially supported although histomorphometry disclosed no significant difference in nerve fiber regeneration between the different experimental groups. Therefore, results suggest that enrichment of equine type III collagen membrane with the N1E-115 cellular system in the rat sciatic nerve crush model may support recovery, at least in terms of motor function. The discrepancy between functional and morphological results also suggests that the combined use of functional and morphological analysis should be recommended for an overall assessment of recovery in nerve regeneration studies.

Functional and morphological assessment of a standardized crush injury of the rat median nerve

The availability of effective experimental models for investigating nerve regeneration and designing new strategies for promoting this unique repair process is important. The aim of this study was to standardize a rat median nerve crush injury model using a non-serrated clamp exerting a compression force of 17.02 MPa for a duration of 30s. Results showed that functional recovery, evaluated by grasping test, was already detectable at day-12 and progressively increased until day-28 after which animal performance plateaued until the end of testing (day-42), reaching a range of 75-80% of pre-operative values. Morphological analysis on the median nerve segments, distal to the crush lesion, which were withdrawn at the end of the experiment showed that regenerated nerve fibers are significantly more numerous and densely packed; they are also smaller and have a thinner myelin sheath compared to controls. Together, these results provide a baseline characterization of the crush median nerve injury experimental model for its employment in the investigation of nerve regeneration research, especially when a reproducible regeneration process is required, such as for the study of biological mechanisms of peripheral nerve fiber regeneration or development of new therapeutic agents for promoting posttraumatic nerve repair.

Use of hybrid chitosan membranes and N1E-115 cells for promoting nerve regeneration in an axonotmesis rat model

Many studies have been dedicated to the development of scaffolds for improving post-traumatic nerve regeneration. The goal of this study was to develop and test hybrid chitosan membranes to use in peripheral nerve reconstruction, either alone or enriched with N1E-115 neural cells. Hybrid chitosan membranes were tested in vitro, to assess their ability in supporting N1E-115 cell survival and differentiation, and in vivo to assess biocompatibility as well as to evaluate their effects on nerve fiber regeneration and functional recovery after a standardized rat sciatic nerve crush injury. Functional recovery was evaluated using the sciatic functional index (SFI), the static sciatic index (SSI), the extensor postural thrust (EPT), the withdrawal reflex latency (WRL) and ankle kinematics. Nerve fiber regeneration was assessed by quantitative stereological analysis and electron microscopy. All chitosan membranes showed good biocompatibility and proved to be a suitable substrate for plating the N1E-115 cellular system. By contrast, in vivo nerve regeneration assessment after crush injury showed that the freeze-dried chitosan type III, without N1E-115 cell addition, was the only type of membrane that significantly improved posttraumatic axonal regrowth and functional recovery. It can be thus suggested that local enwrapping with this type of chitosan membrane may represent an effective approach for the improvement of the clinical outcome in patients receiving peripheral nerve surgery.

Long-term functional and morphological assessment of a standardized rat sciatic nerve crush injury with a non-serrated clamp

We have recently described the sequence of functional and morphologic changes occurring after a standardized sciatic nerve crush injury. An 8-week post-injury time was used because this end point is the far most used. Unexpectedly, both functional and morphological data revealed that animals had still not recovered to normal pre-injury levels. Therefore, the present study was designed in order to prolong the observation up to 12 weeks. Functional recovery was evaluated using sciatic functional index (SFI), static sciatic index (SSI), extensor postural thrust (EPT), withdrawal reflex latency (WRL) and ankle kinematics. In addition, quantitative morphology was carried out on regenerated nerve fibers. A full functional recovery was predicted by SFI/SSI, EPT and WRL but not all ankle kinematics parameters. Moreover, only two morphological parameters (myelin thickness/axon diameter ratio and fiber/axon diameter ratio) returned to normal values. Data presented in this paper provide a baseline for selecting the adequate end-point and methods of recovery assessment for a rat sciatic nerve crush study and suggest that the combined use of functional and morphological analysis should be recommended in this experimental model.

Primary and secondary tumours occurring simultaneously in the brain of a dog

Primary brain tumours of a single histological type and metastatic brain tumours are well described in dogs in the current veterinary literature. However, the concurrent presence of a primary and secondary tumour in the brain of a dog has never, to the authors' knowledge, been previously reported. The clinical and pathological features of a nine-year-old, female boxer with an oligodendroglioma and metastases from a mammary gland adenocarcinoma occurring simultaneously in the brain are described in this case report. Information in the veterinary literature on multiple malignancies affecting the central nervous system is very limited; therefore, a discussion about comparative situations in human medicine has been included.