Improved nerve regeneration with neutralization of transforming growth factor-beta1

Perineurial Glial Plasticity and the Role of TGF-β in the Development of the Blood-Nerve Barrier

Precisely orchestrated interactions between spinal motor axons and their ensheathing glia are vital for forming and maintaining functional spinal motor nerves. Following perturbations to peripheral myelinating glial cells, centrally derived oligodendrocyte progenitor cells (OPCs) ectopically exit the spinal cord and myelinate peripheral nerves in myelin with CNS characteristics. However, whether remaining peripheral ensheathing glia, such as perineurial glia, properly encase the motor nerve despite this change in glial cell and myelin composition, remains unknown. Using zebrafish mutants in which OPCs migrate out of the spinal cord and myelinate peripheral motor axons, we assayed perineurial glial development, maturation, and response to injury. Surprisingly, in the presence of OPCs, perineurial glia exited the CNS normally. However, aspects of their development, response to injury, and function were altered compared with wildtype larvae. In an effort to better understand the plasticity of perineurial glia in response to myelin perturbations, we identified transforming growth factor-β1 as a partial mediator of perineurial glial development. Together, these results demonstrate the incredible plasticity of perineurial glia in the presence of myelin perturbations.SIGNIFICANCE STATEMENT Peripheral neuropathies can result from damage or dysregulation of the insulating myelin sheath surrounding spinal motor axons, causing pain, inefficient nerve conduction, and the ectopic migration of oligodendrocyte progenitor cells (OPCs), the resident myelinating glial cell of the CNS, into the periphery. How perineurial glia, the ensheathing cells that form the protective blood-nerve barrier, are impacted by this myelin composition change is unknown. Here, we report that certain aspects of perineurial glial development and injury responses are mostly unaffected in the presence of ectopic OPCs. However, perineurial glial function is disrupted along nerves containing centrally derived myelin, demonstrating that, although perineurial glial cells display plasticity despite myelin perturbations, the blood-nerve barrier is compromised in the presence of ectopic OPCs.

The Influence of Neurodevelopmental Treatment on Transforming Growth Factor-β1 Levels and Neurological Remodeling in Children With Cerebral Palsy

Neurodevelopmental treatment is an advanced therapeutic approach for the neural rehabilitation of children with cerebral palsy. Cerebral palsy represents a spectrum of neurological disorders primarily affecting gross motor function. The authors investigated the effects of neurodevelopmental treatment on serum levels of transforming growth factor-β1 (TGF-β1), a neuroprotective cytokine, and improvements to motor skills. Serum TGF-β1 levels and total score of the Gross Motor Function Measure-88 (GMFM-88) were significantly higher in children with cerebral palsy who underwent neurodevelopmental treatment compared to untreated patients (P < .01). Furthermore, the improved GMFM-88 total scores after neurodevelopmental treatment were significantly higher in children under the age of 3 with cerebral palsy than in older patients (P < .01). The authors demonstrate that the integration of TGF-β1 levels and GMFM-88 total score could be used to assess the efficacy of neurodevelopmental treatment. Moreover, the findings provide further scientific support for the early intervention and neurological rehabilitation of young children with cerebral palsy.

Mannose-6-phosphate facilitates early peripheral nerve regeneration in thy-1-YFP-H mice

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We have visualized and quantified nerve regeneration at an axonal level.

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Axons cross the repair site more directly following mannose-6-phosphate treatment.

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Mannose-6-phosphate alters axon sprouting just distal to axon entry into the graft.

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Mannose-6-phosphate may enable more favorable collagen fibril alignment.

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Our data add further evidence that mannose-6-phosphate improves nerve regeneration.

The formation of scar tissue following nerve injury has been shown to adversely affect nerve regeneration and evidence suggests that mannose-6-phosphate (M6P), a potential scar reducing agent that affects transforming growth factor (TGF)-β activation, may enhance nerve regeneration. In this study we utilized thy-1-YFP-H mice – a transgenic strain expressing yellow fluorescent protein (YFP) within a subset of axons – to enable visual analysis of axons regenerating through a nerve graft. Using this strain of mouse we have developed analysis techniques to visualize and quantify regeneration of individual axons across the injury site following the application of either M6P or vehicle to the site of nerve injury.

No significant differences were found in the proportion of axons regenerating through the graft between M6P- and vehicle-treated grafts at any point along the graft length. Maximal sprouting occurred at 1.0 mm from the proximal graft ending in both groups. The maximum change in sprouting levels for both treatment groups occurred between the graft start and 0.5-mm interval for both treatment groups. The difference between repair groups was significant at this point with a greater increase seen in the vehicle group than the M6P group. The average length of axons regenerating across the initial graft entry was significantly shorter in M6P- than in vehicle-treated grafts, indicating that they encountered less impedance.

Application of M6P appears to reduce the disruption of regenerating axons and may therefore facilitate quicker recovery; this is likely to result from altered scar tissue formation in M6P grafts in the early stages of recovery. This study also establishes the usefulness of our methods of analysis using the thy-1-YFP-H mouse strain to visualize and quantify regeneration at the level of the individual axon.

Effect of delayed peripheral nerve repair on nerve regeneration, Schwann cell function and target muscle recovery

Despite advances in surgical techniques for peripheral nerve repair, functional restitution remains incomplete. The timing of surgery is one factor influencing the extent of recovery but it is not yet clearly defined how long a delay may be tolerated before repair becomes futile. In this study, rats underwent sciatic nerve transection before immediate (0) or 1, 3, or 6 months delayed repair with a nerve graft. Regeneration of spinal motoneurons, 13 weeks after nerve repair, was assessed using retrograde labeling. Nerve tissue was also collected from the proximal and distal stumps and from the nerve graft, together with the medial gastrocnemius (MG) muscles. A dramatic decline in the number of regenerating motoneurons and myelinated axons in the distal nerve stump was observed in the 3- and 6-months delayed groups. After 3 months delay, the axonal number in the proximal stump increased 2–3 folds, accompanied by a smaller axonal area. RT-PCR of distal nerve segments revealed a decline in Schwann cells (SC) markers, most notably in the 3 and 6 month delayed repair samples. There was also a progressive increase in fibrosis and proteoglycan scar markers in the distal nerve with increased delayed repair time. The yield of SC isolated from the distal nerve segments progressively fell with increased delay in repair time but cultured SC from all groups proliferated at similar rates. MG muscle at 3- and 6-months delay repair showed a significant decline in weight (61% and 27% compared with contra-lateral side). Muscle fiber atrophy and changes to neuromuscular junctions were observed with increased delayed repair time suggestive of progressively impaired reinnervation. This study demonstrates that one of the main limiting factors for nerve regeneration after delayed repair is the distal stump. The critical time point after which the outcome of regeneration becomes too poor appears to be 3-months.

Histomorphometric changes in repaired mouse sciatic nerves are unaffected by the application of a scar-reducing agent

Microsurgical repair of transected peripheral nerves is compromised by the formation of scar tissue and the development of a neuroma, thereby limiting the success of regeneration. The aim of this study was to quantify histomorphometrically the structural changes in neural tissue that result from repair, and determine the effect of mannose-6-phosphate (M6P), a scar-reducing agent previously shown to enhance regeneration. In anaesthetised C57-black-6 mice, the left sciatic nerve was sectioned and repaired using four epineurial sutures. Either 100 μL of 600 mm M6P (five animals) or 100 μL of phosphate-buffered saline (placebo controls, five animals) was injected into and around the nerve repair site. A further group acted as sham-operated controls. After recovery for 6 weeks, the nerve was harvested for analysis using light and electron microscopy. Analysis revealed that when compared with sham controls, myelinated axons had smaller diameters both proximal and distal to the repair. Myelinated axon counts, axonal density and size all decreased across the repair site. There were normal numbers and densities of non-myelinated axons both proximal and distal to the repair. However, there were more Remak bundles distal to the repair site, and fewer non-myelinated axons per Remak bundle. Application of M6P did not affect any of these parameters.

The effect of melatonin and platelet gel on sciatic nerve repair: an electrophysiological and stereological study

Nerve regeneration after surgical reconstruction is far from optimal, and thus effective strategies for improving the outcome of nerve repair are being sought. In this experiment, we verified if postoperative intraperitoneal melatonin (MLT) administration after intraoperative platelet gel application improves peripheral nerve regeneration. In adult male rats, 1-cm long sciatic nerve defects were repaired using four different strategies: autologous nerve graft repair followed by MLT (NM, n = 5), collagen conduit repair followed by MLT (CM, n = 5), platelet gel-enriched collagen conduit repair followed by MLT (CGM, n = 6), and platelet gel-enriched collagen conduit (CG, n = 5) repair followed by no substance administration. Sham operated animals were used as controls (Cont, n = 5). Ninety days after surgery, the nerve regeneration outcome was comparatively assessed by means of electrophysiological and stereological analysis. Electrophysiology revealed no significant differences between the experimental and the sham control groups. Stereological analysis showed no significant differences among the experimental groups regarding axon size and myelin thickness, but the axon number was significantly lower in the CM compared to Cont and NM group. Moreover, there was no significant difference between number of axons in CG and Cont groups, between CGM and CM, and between CM and NM. Although it was observed that platelet gel have a positive effect on nerve regeneration, but a combination of local platelet gel with MLT does not have the same effect on nerve repair.

The effect of Mannose-6-Phosphate on recovery after sciatic nerve repair

We have determined the effect of applying Mannose-6-Phosphate (M6P), a scar reducing agent, to a site of sciatic nerve repair. In anaesthetised C57-Black-6 mice, the left sciatic nerve was sectioned and repaired using 4 epineurial sutures. Either 100 μl of 600 mM Mannose-6-Phosphate (29 animals), or 100 μl of phosphate buffered saline as a placebo control (29 animals), was injected into and around the nerve repair site. A further group acted as sham-operated controls. After 6 or 12 weeks of recovery the extent of regeneration was assessed electrophysiologically and the percentage area of collagen staining at the repair site was analysed using picrosirius red and image analysis. Gait analysis was undertaken pre-operatively and at 1, 3, 6, 9 and 12 weeks postoperatively, to assess functional recovery. At 6 weeks the compound action potentials recorded from the regenerated nerves in the M6P group were significantly larger than in the placebo controls (P=0.015), and the conduction velocities were significantly faster (P=0.005), but there were no significant differences between these groups at 12 weeks. Gait analysis suggested better early functional recovery in the M6P group. In both repair groups there was a significant reduction in collagen staining between 6 and 12 weeks, suggestive of scar remodelling. We conclude that the normal scar remodelling process aids long term recovery in repaired nerves. Administration of 600 mM M6P to the nerve repair site enhances nerve regeneration and functional recovery in the early stages, and may lead to improved outcomes.

Significant reduction in neural adhesions after administration of the regenerating agent OTR4120, a synthetic glycosaminoglycan mimetic, after peripheral nerve injury in rats

OBJECT

Extradural and intraneural scar formation after peripheral nerve injury frequently causes tethering and compression of the nerve as well as inhibition of axonal regeneration. Regenerating agents (RGTAs) mimic stabilizing and protective properties of sulphated glycosaminoglycan toward heparin-binding growth factors. The aim of this study was to assess the effect of an RGTA known as OTR4120 on extraneural fibrosis and axonal regeneration after crush injury in a rat sciatic nerve model.

METHODS

Thirty-two female Wistar rats underwent a standardized crush injury of the sciatic nerve. The animals were randomly allocated to RGTA treatment or sham treatment in a blinded design. To score neural adhesions, the force required to break the adhesions between the nerve and its surrounding tissue was measured 6 weeks after nerve crush injury. To assess axonal regeneration, magnetoneurographic measurements were performed after 5 weeks. Static footprint analysis was performed preoperatively and at Days 1, 7, 14, 17, 21, 24, 28, 35, and 42 postoperatively.

RESULTS

The magnetoneurographic data show no significant difference in conduction capacity between the RGTA and the control group. In addition, results of the static footprint analysis demonstrate no improved or accelerated recovery pattern. However, the mean pullout force of the RGTA group (67 +/- 9 g [mean +/- standard error of the mean]) was significantly (p < 0.001) lower than that of the control group (207 +/- 14 g [mean +/- standard error of the mean]).

CONCLUSIONS

The RGTAs strongly reduce nerve adherence to surrounding tissue after nerve crush injury.

A drug delivery system for the treatment of peripheral nervous system injuries

Recent results in biomedical engineering and materials science and technology have brought about the development of novel bioactive materials by which the repair of peripheral nervous system injuries can be improved. The formation of scarring tissue, which represents a physical barrier to axon elongation, and the not oriented outgrowth of neurites are the two major obstacles for a complete recovery of physiological nerve function. This study mainly focuses on the analysis of biocompatible constructs for the controlled release of anti-scarring antibodies by means of fluorescence spectroscopy techniques.

Notch2 negatively regulates myofibroblastic differentiation of myoblasts

Myofibroblasts are one of the key cellular components involved in fibrosis of skeletal muscle as well as in other tissues. Transforming growth factor-beta1 (TGF-beta1) stimulates differentiation of mesenchymal cells into myofibroblasts, but little is known about the regulatory mechanisms of myofibroblastic differentiation. Since Notch2 was shown to be downregulated in TGF-beta1-induced non-muscle fibrogenic tissue, we investigated whether Notch2 also has a distinctive role in myofibroblastic differentiation of myogenic cells induced by TGF-beta1. TGF-beta1 treatment of C2C12 myoblasts led to expression of myofibroblastic marker alpha-smooth muscle actin (alpha-SMA) and collagen I with concomitant downregulation of Notch2 expression. Overexpression of active Notch2 inhibited TGF-beta1-induced expression of alpha-SMA and collagen I. Interestingly, transient knockdown of Notch2 by siRNA in C2C12 myoblasts and primary cultured muscle-derived progenitor cells resulted in differentiation into myofibroblastic cells expressing alpha-SMA and collagen I without TGF-beta1 treatment. Furthermore, we found Notch3 was counter-regulated by Notch2 in C2C12 cells. These findings suggest that Notch2 is inhibiting differentiation of myoblasts into myofibroblasts with downregulation of Notch3 expression.

Nanofunctionalisation for the treatment of peripheral nervous system injuries

A construct based on the electrostatic layer-by-layer self assembly technique has been fabricated, to be used as a tailored device to encourage nerve regeneration. A multilayered nanocoating composed by three precursor bilayers of cationic and anionic polyelectrolytes followed by bilayers of poly-D-lysine (PDL) and antibody specific to Transforming Growth Factor beta1 (anti-TGF-beta1) has been deposited on HYAFF 11. Initially the assembly process has been monitored by quartz crystal microbalance (QCM) in order to select the optimal working conditions for nanocoating deposition. Structural studies of the resulting multilayers confirmed stepwise deposition of anti-TGF-beta1 with an average layer thickness of 2.6 nm and an average layer mass of 117 ng. Atomic Force Microscopy has been used to characterize multilayer uniformity. Finally, the immunological activity of the multilayered structure has been assessed. The results show that anti-TGF-beta1 can be included in its active form in a predetermined multilayered structure onto HYAFF11 with quantitative control of layer thickness and weight, providing a high potential tool in tissue engineering.

The effect of antibodies to TGF-beta1 and TGF-beta2 at a site of sciatic nerve repair

Scar formation at a site of nerve injury can cause a mechanical barrier to axonal regeneration and lead to the development of multiple axonal sprouts to form a neuroma. We have investigated the hypothesis that the application of a scar-preventing agent to a nerve repair site would enhance regeneration of the nerve and reduce neuroma formation. The left sciatic nerve was exposed under general anaesthesia in 18 adult Sprague-Dawley rats. In 12 animals, the nerve was sectioned and immediately re-approximated using four epineurial sutures, and in 6 of these animals neutralising antibodies to transforming growth factor (TGF)-beta1 and TGF-beta2 were injected into and around the repair site. The six other animals acted as controls. After 7 weeks, the outcome was assessed by recording compound action potential (CAP) ratios, measuring collagen levels using picrosirius red staining, and counting the number of myelinated axons proximal and distal to the repair. After repair alone, the mean percentage of area of staining (PAS) for collagen within the nerve had significantly increased. However, after repair with the administration of antibodies, the PAS was not significantly different from that in the sham controls. After administration of antibodies, the CAP ratios were significantly smaller than in controls but not after repair alone. In both nerve injury groups, the myelinated fibre counts were significantly increased distal to the injury site, but there was no difference between these two groups. We conclude that administration of antibodies to TGF-beta1 and TGF-beta2 reduced scar formation at the repair site but did not enhance regeneration of the nerve or reduce the development of multiple axonal sprouts.

Scarring impedes regeneration at sites of peripheral nerve repair

We have investigated the effect of scarring at a site of peripheral nerve repair by comparing regeneration of the sciatic nerve in normal mice and two transgenic strains with an increased or decreased propensity for scarring. The outcome was assessed by quantifying collagen at the repair site, recording compound action potentials and counting myelinated nerve fibres on each side of the repair. We found that higher levels of collagen scar formation were associated with smaller compound action potentials, slower conduction velocities and a reduction in fibre numbers across the repair site. We conclude that scarring impedes regeneration at sites of nerve repair and suggest that this could be amenable to therapeutic manipulation.

Immunohistochemical profile of transforming growth factor-β1 and basic fibroblast growth factor in sciatic nerve anastomosis following pinealectomy and exogenous melatonin administration in rats

Collagen scar formation at the cut end of a peripheral nerve, an important problem in clinical practice for neurosurgeons, obstructs sprouting of axons into appropriate distal fascicles, and thereby limits the regeneration process. Researchers have attempted to control collagen accumulation and neuroma formation with various physical and chemical methods, but with limited functional success. Recently, it has been demonstrated that transforming growth factor (TGF)-beta and basic fibroblast growth factor (bFGF) play an important role in collagen production by fibroblasts and in Schwann cell activity. In our study, rats were divided into a control group, a melatonin-treated group, a surgical pinealectomy group, and a group treated with melatonin following pinealectomy. They then underwent a surgical sciatic nerve transection and primary suture anastomosis. At 2 months after anastomosis, the animals were sacrificed and unilateral sciatic nerve specimens, including the anastomotic region, were removed and processed for immunohistochemical study from two animals in each group. For each antibody, immunoreactivity was assessed using a semiquantitative scoring system. Strong TGF-beta1 and/or bFGF expression was observed in the epineurium of animals that underwent pinealectomy, but no or weak staining was observed in animals in the control and melatonin treatment groups. Based on these data, we suggest that both TGF-beta1 and bFGF have important roles in control of collagen accumulation and neuroma formation at the anastomotic site, and that the pineal neurohormone melatonin has a beneficial effect on nerve regeneration.

Inferior Alveolar Nerve Transposition—An In Vitro Comparison Between Piezosurgery and Conventional Bur Use

An in vitro comparison between a new ultrasound-based piezoelectric device and a conventional bur was performed for lateralization or transposition of the inferior alveolar nerve to evaluate the effects on soft and hard tissue. Transposition of the inferior alveolar nerve was performed in the cadaver mandibles of 10 sheep: the left nerve was uncovered with a saline-cooled diamond-coated spherical bur (2000 rpm), and the right nerve was uncovered with the piezoelectric device mounted with a spherical diamond tip. The surface, the zone of bone defect, and the nerve were examined by light microscopy and laser microscopy. Bone treated with the rotary bur showed significantly smoother surfaces and shallower defect zones (50 microm) in comparison with the piezoelectric device (150 microm). Lesions of the epineurium and an increased amount of bone particles were found in the lesions prepared with the piezoelectric device. In vitro preparation with the piezoelectric device was more invasive to the bone than was a conventional diamond bur. Touching the inferior alveolar nerve resulted in roughening of the epineurium without affecting deeper structures. The degree of injury was lower than when using the conventional rotary bur.

Cytokine responses during chronic denervation

Background

The aim of the present study was to examine inflammatory responses during Wallerian degeneration in rat peripheral nerve when the regrowth of axons was prevented by suturing.

Methods

Transected rat sciatic nerve was sutured and ligated to prevent reinnervation. The samples were collected from the left sciatic nerve distally and proximally from the point of transection. The endoneurium was separated from the surrounding epi- and perineurium to examine the expression of cytokines in both of these compartments. Macrophage invasion into endoneurium was investigated and Schwann cell proliferation was followed as well as the expression of cytokines IL-1β, IL-10, IFN-γ and TNF-α mRNA. The samples were collected from 1 day up to 5 weeks after the primary operation.

Results

At days 1 to 3 after injury in the epi-/perineurium of the proximal and distal stump, a marked expression of the pro-inflammatory cytokines TNF-α and IL-1β and of the anti-inflammatory cytokine IL-10 was observed. Concurrently, numerous macrophages started to gather into the epineurium of both proximal and distal stumps. At day 7 the number of macrophages decreased in the perineurium and increased markedly in the endoneurium of both stumps. At this time point marked expression of TNF-α and IFN-γ mRNA was observed in the endo- and epi-/perineurium of the proximal stump. At day 14 a marked increase in the expression of IL-1β could be noted in the proximal stump epi-/perineurium and in the distal stump endoneurium. At that time point many macrophages were observed in the longitudinally sectioned epineurium of the proximal 2 area as well as in the cross-section slides from the distal stump. At day 35 TNF-α, IL-1β and IL-10 mRNA appeared abundantly in the proximal epi-/perineurium together with macrophages.

Conclusion

The present studies show that even during chronic denervation there is a cyclic expression pattern for the studied cytokines. Contrary to the previous findings on reinnervating nerves the studied cytokines show increased expression up to 35 days. The high expressions of pro-inflammatory and anti-inflammatory cytokines in the proximal epi-/perineurial area at day 35 may be involved in the formation of fibrosis due to irreversible nerve injury and thus may have relevance to the formation of traumatic neuroma.

Pinealectomy exaggerates and melatonin treatment suppresses neuroma formation of transected sciatic nerve in rats: gross morphological, histological and stereological analysis

At present, an intensive effort for prevention of neuroma formation following peripheral nerve section continues. It has been recently suggested that surgical pinealectomy (Px) induces elevation of the collagen content in the granulation tissue of a wound, while melatonin application after Px suppresses elevation of the collagen accumulation in the tissue. The aim of the present study was to assess whether melatonin had the ability to suppress collagen production and neuroma formation following peripheral nerve transection. A total of 40 male rats (four groups of 10) were left intact (intact controls) or sham operated (sham group), were Px, or were Px and given melatonin (Px + melatonin group). All animals underwent a surgical intervention consisting of right sciatic nerve neurectomy. After 4 wk, the animals were killed following intracardiac perfusion. Gross morphology of neuroma formation in the proximal nerve segment was examined and proximal neuroma evaluated. Macroscopic and microscopic findings revealed that Px caused a proliferation of connective tissue and large neuroma formation at the proximal ends of transected nerves. Stereological analysis showed that there was a statistically significant reduction in connective tissue content of the same region in Px animals treated with melatonin (P < 0.005). The results achieved in a rodent model of sciatic nerve neuroma formation showed that there was a positive correlation between macroscopic and microscopic observations, and that melatonin enhanced axonal regeneration presumably due to its inhibitory effect on neuroma formation.

Distinct expression of TGF-beta1 mRNA in the endo- and epineurium after nerve injury

TGF-beta is a multifunctional regulatory protein with important effects on cell proliferation and differentiation, immune reactivity and extracellular matrix (ECM). During peripheral regeneration it can have growth promoting effects for axonal sprouting, but on the other hand, it may be involved in epineurial scarring and neuroma formation. We studied the expression of TGF-beta1 mRNA in the rat peripheral nerve with real time-PCR at 1, 3, 5, 7, 14, 21, 28, 35, and 42 days after transection. The sciatic nerve was sutured after transection to prevent axonal regeneration. Samples from both proximal and distal stumps were collected. To distinguish the possible different expression in the endo- and epineurium these two compartments were studied separately. The most significant finding was observed in the epineurium of the proximal stump 35 days after the operation. The expression of TGF-beta1 mRNA was over 700 times higher than that found in the non-operated controls. At the same time the expression of TGF-beta1 mRNA in the endoneurium was only twice as high as the values measured from the non-operated controls. Distally the TGF-beta1 mRNA expression in the endoneurium reached its peak after 2 weeks, and at weeks 3-6, the expression was two to four times higher than in the controls. This study supports the concept that TGF-beta1 can affect epineurial scarring.

Contralateral non-operated nerve to transected rat sciatic nerve shows increased expression of IL-1beta, TGF-beta1, TNF-alpha, and IL-10

Recent reports indicate that after a peripheral nerve injury, the uninjured contralateral nerve is also affected. Because cytokines play an important role in the peripheral nerve injury, we studied the expression of five different mRNAs (interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), interleukin-10 (IL-10), transforming growth factor-beta1 (TGF-beta1) and interleukin-4 (IL-4)) in the contralateral, non-operated, left sciatic nerve when the right rat sciatic nerve was transected. This study extended up to 42 days after the transection. No IL-4 expression was noted. During the first 3 days, high expression of the other studied cytokines was noted in the endoneurium. At day 7, the expression diminished to the control levels. After this, a cyclic expression pattern appeared, which was most pronounced in the endoneurium at 35 days. We also show that the expression pattern in the endoneurium is different from that in the surrounding epi- and perineurium. Also, our present study shows clearly that contralateral nerves are poor controls after injury.

Gene expression of transforming growth factor beta isoforms in interposition nerve grafting

Scar production and neuroma formation at nerve graft coaptation sites may limit axonal regeneration and impair functional outcome. Transforming growth factor beta (TGF-beta) is a family of growth factors that is involved in scar formation, wound healing, and nerve regeneration. Fifteen adult Sprague-Dawley rats underwent autogenous nerve grafting. The nerve grafts were analyzed by in situ hybridization to determine the temporal and spatial expression of TGF-beta1 and TGF-beta3 messenger RNA (mRNA). The grafted nerves showed increased expression of TGF-beta1 and TGF-beta3 mRNA in the nerve and the surrounding connective tissue during the first postoperative week. These data suggest that modulation of TGF-beta levels in the first postoperative week may be effective in helping to control scar formation and improve nerve regeneration.

Distribution of TGF-beta, the TGF-beta type I receptor and the R-II receptor in peripheral nerves and mechanoreceptors; observations on changes after traumatic injury

The mechanisms governing the regeneration of denervated peripheral mechanoreceptors are similar to those of peripheral nerves. The ability to regenerate depends partly on changes of the Schwann cell phenotype. The transforming growth factor beta (TGF-beta) family have been implicated in induction of Schwann cell proliferation, production of extracellular matrix and neurotrophin synthesis as well as synthesis or repression of cell adhesion molecules. Hence, they may prove to be of importance for regenerative mechanisms in peripheral mechanoreceptors. The distribution of TGF-beta, the receptors I and II and intra-cellular second messengers, Smad 2/3 and 4 was assessed in sensory neurones, peripheral nerves and mechanoreceptors by immuno-histochemistry, immuno-electron microscopy and in situ hybridisation. TGF-beta2 mRNA and TGF-beta2-like immunoreactivity (IR) were expressed in injured small and medium sized rat sensory neurones of dorsal root ganglia. TGF-beta and receptor II mRNA and immunoreactivities (IR) were present in satellite cells. Intact and injured sensory neurones expressed receptor I mRNA and Smad 2 mRNA. TGF-beta2 mRNA was found in transected nerve stumps and in sensory mechanoreceptors. TGF-beta1, 2 and Smad 4 were also observed in inner core lamellar cells of intact and denervated cat Pacinian corpuscles. Lamellar cells of intact and denervated Meissner corpuscles were TGF-beta immunoreactive. Merkel cells were receptors I and II immunoreactive. In conclusion, cutaneous and subcutaneous mechanoreceptors differ with regard to the expression of TGF-beta isoforms and receptors.

Neurologic erectile dysfunction

Neurologic erectile dysfunction presents a diagnostic and treatment challenge to the internist and urologist. Multiple chronic disease modalities and traumatic etiologies exist. Education regarding these conditions and a detailed and thorough history and office work-up are the best resources for the clinician. Treatment can follow the model of proceeding from the least to most invasive procedure (process of care), taking into account patient and partner satisfaction. Because the psychology of grief and loss may enter into treatment of some neurologic conditions (e.g., erectile dysfunction after radical retropubic prostatectomy, spinal cord injury, or chronic diseases), a whole-patient approach encompassing psychotherapy is warranted.