Immunohistochemical labelling of components of the endoneurial extracellular matrix of intact and rhizotomized dorsal and ventral spinal roots of the rat--a quantitative evaluation using image analysis

Endoneurial extracellular matrix influences regeneration and maturation of motor nerve axons--a model of acellular nerve graft

Clinical results of functional reinnervation after application of autogeneous nerve grafts obtained from cutaneous nerves have not always been satisfactory. A foreign extracellular condition especially for regeneration of motor axons is assumed to be one of the reasons explaining these unsuccessful results. The role of endoneurial extracellular matrix in regeneration and maturation of motor axons was studied using acellular nerve segment prepared from muscular or cutaneous nerves applied between stumps of transected motor branch of the femoral nerve. No differences were found in the numbers of regenerated axons and related motoneurons through the motor and cutaneous nerve grafts 1 month after operation. Two months from grafting, however, the numbers of motoneurons and regenerated axons were increased significantly in the motor grafts while these were decreased after regeneration through the cutaneous grafts compared with 1 month. Axons' diameter and thickness of their myelin sheaths were similar in the cutaneous grafts 1 and 2 months after grafting. In comparison to 1 month, axons had larger diameter and thicker myelin in the motor than cutaneous nerve grafts 2 months from their application. Results of morphometric analysis indicate more beneficial extracellular conditions for regeneration and maturation of myelinated motor nerve axons in the acellular motor than cutaneous nerve graft. Generally, the results revealed that the endoneurial extracellular matrix of motor fibers has a positive effect on regeneration and maturation of motor nerve axons after lesion.

Extracellular matrix remodelling in human diabetic neuropathy

The extracellular matrix of peripheral nerve plays a vital role in terms of normal nerve fibre function and also in the regenerative response following nerve injury. Nerve fibre loss is a major feature of diabetic neuropathy; however, the regenerative response is limited and this may be associated with changes in the composition of the extracellular matrix. Glycoproteins and collagens are major components of the extracellular matrix and are known to be important in terms of axonal growth. This work has therefore examined whether changes in the expression of two major glycoproteins, laminin and tenascin, and three collagen types (IV, V and VI) occur in the endoneurial and perineurial connective tissue compartments of human diabetic nerve. Despite being known to have a positive effect in terms of axonal growth, laminin levels were not elevated in the diabetic nerves. However, the pattern of tenascin expression did differ between the two groups being found in association with axon myelin units in the diabetic samples only. The pattern of collagen IV expression was the same in both tissue groups and was not found to be up-regulated. However, levels of collagen V and VI were both significantly increased in the endoneurium and for collagen VI also in the perineurium.

The role of thrombospondin-1 and transforming growth factor-beta after spinal cord injury in the rat

Spinal cord injury (SCI) continues to result in high morbidity and mortality throughout the world. An effective neuroprotective agent is still not available to counteract secondary damage caused by traumatic injury. Thrombospondin-1 (TSP-1) and transforming growth factor-beta (TGF-beta) have a role in angiogenesis, scar deposition, inflammation and may affect astrocyte phenotype and mobility. We investigated the role of TSP-1 and TGF-beta in a model of spinal cord injury in rats. Forty female Sprague-Dawley rats were randomly divided into two equal groups: the experimental group was subject to SCI using an impactor and the sham-operated group was not subject to SCI. These animals were sacrificed at 12 h and 24 h after SCI for immunochemistry and Western blot analysis of the injured spinal segment for the expression of the TSP-1 and TGF-beta proteins. We found that TSP-1 and TGF-beta expression increased immediately after SCI in the injured segment. After 12 h, TSP-1 concentrations increased more rapidly and dramatically than TGF-beta in the injured segment of the spinal cord. Elevations in TSP-1 and TGF-beta concentrations persisted for 24 h after injury. These results show that elevated expression of TSP-1 and TGF-beta can be detected in the injured segment of the spinal cord 12 and 24 h after injury. Thus, TSP-1 and TGF-beta may have a role in SCI.