Erythropoietin promotes peripheral nerve regeneration in rats by upregulating expression of insulin-like growth factor-1

Introduction

Erythropoietin (EPO) has been shown to have beneficial effects on peripheral nerve damage, but its mechanism of action remains incompletely understood. In this study we hypothesized that EPO promotes peripheral nerve repair via neurotrophic factor upregulation.

Material and methods

Thirty adult male Wistar rats were employed to establish a sciatic nerve injury model. They were then randomly divided into two groups to be subjected to different treatment: 0.9% saline (group A) and 5000 U/kg EPO (group B). The walking behavior of rats was evaluated by footprint analysis, and the nerve regeneration was assessed by electron microscopy. The expression of insulin-like growth factor-1 (IGF-1) in the injured sciatic nerves was detected by immunohistochemical analysis.

Results

Compared to saline treatment, EPO treatment led to the growth of myelin sheath, the recovery of normal morphology of axons and Schwann cells, and higher density of myelinated nerve fibers. Erythropoietin treatment promoted the recovery of SFI in the injured sciatic nerves. In addition, EPO treatment led to increased IGF-1 expression in the injured sciatic nerves.

Conclusions

Erythropoietin may promote peripheral nerve repair in a rat model of sciatic nerve injury through the upregulation of IGF-1 expression. These findings reveal a novel mechanism underlying the neurotrophic effects of EPO.     

Dexamethasone and vitamin B12 synergistically promote peripheral nerve regeneration in rats by upregulating the expression of brain-derived neurotrophic factor

Introduction

Dexamethasone and vitamin B₁₂ are currently used in the clinic to treat peripheral nerve damage but their mechanisms of action remain incompletely understood. In this study we hypothesized that dexamethasone and vitamin B₁₂ promote the production of endogenous neurotrophic factors, thereby enhancing peripheral nerve repair.

Material and methods

Ninety-six adult male Wistar rats were employed to establish a sciatic nerve injury model. They were then randomly divided into 4 groups to be subjected to different treatment: saline (group A), dexamethasone (group B), vitamin B₁₂ (group C), and dexamethasone combined with vitamin B₁₂ (group D). The walking behavior of rats was evaluated by footprint analysis, and the nerve regeneration was assessed by electrophysiological analysis and ultrastructural examination. The expression of brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor, NT-3 and IL-6 in the injured sciatic nerves was detected by immunohistochemical and RT-PCR analysis.

Results

Dexamethasone and vitamin B₁₂ promoted the regeneration of myelinated nerve fibers and the proliferation of Schwann cells. Furthermore, dexamethasone and vitamin B₁₂ promoted the recovery of sciatic functional index and sensory nerve conduction velocity, and upregulated BDNF expression in the injured sciatic nerves.

Conclusions

Dexamethasone and vitamin B₁₂ promote peripheral nerve repair in a rat model of sciatic nerve injury through the upregulation of BDNF expression. These findings provide new insight into the neurotrophic effects of dexamethasone and vitamin B₁₂ and support the application of these agents in clinical treatment of peripheral nerve injury.     

Effects of Intracoronary Administration of Autologous Adipose Tissue-Derived Stem Cells on Acute Myocardial Infarction in a Porcine Model

Purpose

Adipose-derived stem cells (ADSCs) are known to be potentially effective in regeneration of damaged tissue. We aimed to assess the effectiveness of intracoronary administration of ADSCs in reducing the infarction area and improving function after acute transmural myocardial infarction (MI) in a porcine model.

Materials and Methods

ADSCs were obtained from each pig''s abdominal subcutaneous fat tissue by simple liposuction. After 3 passages of 14-days culture, 2 million ADSCs were injected into the coronary artery 30 min after acute transmural MI. At baseline and 4 weeks after the ADSC injection, 99mTc methoxyisobutylisonitrile-single photon emission computed tomography (MIBI-SPECT) was performed to evaluate the left ventricular volume, left ventricular ejection fraction (LVEF; %), and perfusion defects as well as the myocardial salvage (%) and salvage index. At 4 weeks, each pig was sacrificed, and the heart was extracted and dissected. Gross and microscopic analyses with specific immunohistochemistry staining were then performed.

Results

Analysis showed improvement in the perfusion defect, but not in the LVEF in the ADSC group (n=14), compared with the control group (n=14) (perfusion defect, -13.0±10.0 vs. -2.6±12.0, p=0.019; LVEF, -8.0±15.4 vs. -15.9±14.8, p=0.181). There was a tendency of reducing left ventricular volume in ADSC group. The ADSCs identified by stromal cell-derived factor-1 (SDF-1) staining were well co-localized by von Willebrand factor and Troponin T staining.

Conclusion

Intracoronary injection of cultured ADSCs improved myocardial perfusion in this porcine acute transmural MI model.     

Characterization of human adipose-derived stem cells and expression of chondrogenic genes during induction of cartilage differentiation

OBJECTIVES:

Understanding the changes in chondrogenic gene expression that are involved in the differentiation of human adipose-derived stem cells to chondrogenic cells is important prior to using this approach for cartilage repair. The aims of the study were to characterize human adipose-derived stem cells and to examine chondrogenic gene expression after one, two, and three weeks of induction.

MATERIALS AND METHODS:

Human adipose-derived stem cells at passage 4 were evaluated by flow cytometry to examine the expression of surface markers. These adipose-derived stem cells were tested for adipogenic and osteogenic differentiation capacity. Ribonucleic acid was extracted from the cells for quantitative polymerase chain reaction analysis to determine the expression levels of chondrogenic genes after chondrogenic induction.

RESULTS:

Human adipose-derived stem cells were strongly positive for the mesenchymal markers CD90, CD73, CD44, CD9, and histocompatibility antigen and successfully differentiated into adipogenic and osteogenic lineages. The human adipose-derived stem cells aggregated and formed a dense matrix after chondrogenic induction. The expression of chondrogenic genes (collagen type II, aggrecan core protein, collagen type XI, COMP, and ELASTIN) was significantly higher after the first week of induction. However, a significantly elevated expression of collagen type X was observed after three weeks of chondrogenic induction.

CONCLUSION:

Human adipose-derived stem cells retain stem cell characteristics after expansion in culture to passage 4 and serve as a feasible source of cells for cartilage regeneration. Chondrogenesis in human adipose-derived stem cells was most prominent after one week of chondrogenic induction.     

Obstructive Apneas Induce Early Release of Mesenchymal Stem Cells into Circulating Blood

Study Objectives:

To investigate whether noninvasive application of recurrent airway obstructions induces early release of mesenchymal stem cells into the circulating blood in a rat model of obstructive sleep apnea.

Design:

Prospective controlled animal study.

Setting:

University laboratory.

Patients or Participants:

Twenty male Sprague-Dawley rats (250–300 g).

Interventions:

A specially designed nasal mask was applied to the anesthetized rats. Ten rats were subjected to a pattern of recurrent obstructive apneas (60 per hour, lasting 15 seconds each) for 5 hours. Ten anesthetized rats were used as controls.

Measurements and Results:

Mesenchymal stem cells from the blood and bone marrow samples were isolated and cultured to count the total number of colony-forming unit fibroblasts (CFU-F) of adherent cells after 9 days in culture. The number of CFU-F from circulating blood was significantly (P = 0.02) higher in the rats subjected to recurrent obstructive apneas (5.00 ± 1.16; mean ± SEM) than in controls (1.70 ± 0.72). No significant (P = 0.54) differences were observed in CFU-F from bone marrow.

Conclusions:

Application of a pattern of airway obstructions similar to those experienced by patients with sleep apnea induced an early mobilization of mesenchymal stem cells into circulating blood.

Citation:

Carreras A; Almendros I; Acerbi I; Montserrat JM; Navajas D; Farré R. Obstructive apneas induce early release of mesenchymal stem cells into circulating blood. SLEEP 2009;32(1):117-119.     

Co-culture with Schwann cells is an effective way for adipose-derived stem cells neural transdifferentiation

Introduction

Adipose-derived stem cells (ADSCs) could accomplish neural transdifferentiation with the presence of certain growth factors in vitro. It has been proved that bone marrow stromal cells (BMSCs) can realize neural transdifferentiation only by being co-cultured with Schwann cells (SCs), and in our former studies we have confirmed that ADSCs could do so too. This paper aims to investigate whether the neural induction efficiency of co-culture is as high as that of other strategies using chemicals or chemicals combined with some growth factors.

Material and methods

We isolated and multiplied ADSCs from adult Sprague-Dawley rats, and SCs from sciatic nerves of 1-to-2-day-old Sprague-Dawley rat pups, then induced ADSCs neural transdifferentiation through 2% dimethyl sulphoxide (DMSO) and DMSO combined with growth factors. Meanwhile we co-cultured ADSCs and SCs in Transwell culture dishes without intercellular contacts. Immunostaining and RT-PCR were adopted to investigate the neural transdifferentiation of ADSCs. Then we compared the expression differences for genes S100, nestin and GFAP of the above three protocols by real-time PCR.

Results

Both immunostaining and RT-PCR proved that ADSCs could accomplish neural transdifferentiation through each of the above three protocols. And real-time PCR further shows that the gene expression relative quantities for the above three genes are not statistically different between co-culture and induction through DMSO combined with growth factors (p > 0.05), but both of them are statistically different from induction only by DMSO (p < 0.05).

Conclusions

Co-culturing ADSCs and SCs may be a simple, effective and practical way for ADSCs neural transdifferentiation.     

Schwannoma in head and neck: preoperative imaging study and intracapsular enucleation for functional nerve preservation

Purpose

In treating schwannoma patients, it is critical to determine the origin of the tumor to preserve nerve function. We evaluated the validity of preoperative imaging studies in distinguishing the neurological origin of the schwannomas of the head and neck, and the efficacy of intracapsular enucleation in preserving nerve function.

Materials and Methods

In 7 cases of schwannomas in the head and neck region, we predicted whether the tumor originated from the vagus nerve or the cervical sympathetic chain through imaging studies including computed tomography (CT) and magnetic resonance imaging (MRI). All patients were performed intracapsular enucleation, and the function of the vagus nerve and the sympathetic nerve was evaluated preoperatively and postoperatively.

Results

Preoperative imaging studies showed 6 cases where the tumor was located between the carotid artery and the internal jugular vein, and 1 case where the tumor was located posteriorly, displacing the carotid artery and the internal jugular vein anteriorly. At the time of operation, we confirmed schwannoma originating from the vagus nerve on the first 6 cases, and schwannoma originating from the sympathetic nervous system on the last case. All patients went through successful intracapsular enucleation, and of the seven schwannoma cases, 6 patients maintained normal postoperative neurological function (85.7%).

Conclusion

Preoperative imaging studies offer valuable information regarding the location and origination of the tumor, and intracapsular enucleation helped us to preserve the nerve function.     

Unilateral Hypoglossal Nerve Injury in a Collegiate Wrestler: A Case Report

Objective:

To introduce the case of a collegiate wrestler who suffered a traumatic unilateral hypoglossal nerve injury. This case presents the opportunity to discuss the diagnosis and treatment of a 20-year-old man with an injury to his right hypoglossal nerve.

Background:

Injuries to the hypoglossal nerve (cranial nerve XII) are rare. Most reported cases are the result of malignancy, with traumatic causes less common. In this case, a collegiate wrestler struck his head on the wrestling mat during practice. No loss of consciousness occurred. The wrestler initially demonstrated signs and symptoms of a mild concussion, with dizziness and a headache. These concussion symptoms cleared quickly, but the athlete complained of difficulty swallowing (dysphagia) and demonstrated slurred speech (dysarthria). Also, his tongue deviated toward the right. No other neurologic deficits were observed.

Differential Diagnosis:

Occipital-cervical junction fracture, syringomyelia, malignancy, iatrogenic causes, cranial nerve injury.

Treatment:

After initial injury recognition, the athletic trainer placed the patient in a cervical collar and transported him to the emergency department. The patient received prednisone, and the emergency medicine physician ordered cervical spine plain radiographs, brain computed tomography, and brain and internal auditory canal magnetic resonance imaging. The physician consulted a neurologist, who managed the patient conservatively, with rest and no contact activity. The neurologist allowed the patient to participate in wrestling 7 months after injury.

Uniqueness:

To our knowledge, no other reports of unilateral hypoglossal nerve injury from relatively low-energy trauma (including athletics) exist.

Conclusions:

Hypoglossal nerve injury should be considered in individuals with head injury who experience dysphagia and dysarthria. Athletes with head injuries require cranial nerve assessments.     

Conservative and Surgical Treatment Improves Pain and Ankle-Brachial Index in Patients with Lumbar Spinal Stenosis

Purpose

The pathological mechanism of lumbar spinal stenosis is reduced blood flow in nerve roots and degeneration of nerve roots. Exercise and prostaglandin E1 is used for patients with peripheral arterial disease to increase capillary flow around the main artery and improve symptoms; however, the ankle-brachial index (ABI), an estimation of blood flow in the main artery in the leg, does not change after treatment. Lumbar spinal nerve roots contain somatosensory, somatomotor, and unmyelinated autonomic nerves. Improved blood flow by medication with prostaglandin E1 and decompression surgery in these spinal nerve roots may improve the function of nerve fibers innervating muscle, capillary, and main vessels in the lower leg, resulting in an increased ABI. The purpose of the study was to examine whether these treatments can improve ABI.

Materials and Methods

One hundred and seven patients who received conservative treatment such as exercise and medication (n=56) or surgical treatment (n=51) were included. Low back pain and leg pain scores, walking distance, and ABI were measured before treatment and after 3 months of conservative treatment alone or surgical treatment followed by conservative treatment.

Results

Low back pain, leg pain, and walking distance significantly improved after both treatments (p<0.05). ABI significantly increased in each group (p<0.05).

Conclusion

This is the first investigation of changes in ABI after treatment in patients with lumbar spinal stenosis. Improvement of the spinal nerve roots by medication and decompression surgery may improve the supply of blood flow to the lower leg in patients with lumbar spinal stenosis.     

An Implanted Closed-loop Chip System for Heart Rate Control: System Design and Effects in Conscious Rats

Objective

To evaluate the efficiency of an implanted chip system for the control of heart rate (HR).

Methods

The HR was recorded in six conscious Sprague-Dawley (SD) rats. An implanted chip system was designed to regulate the HR by stimulating the right cervical vagus nerve according to the feedback of real time HR. Each rat was subjected to 30-min regulation and 30-min recovery. The change of HR during the regulation period was compared with the control. The ECG was recorded during the experiment for 24 h.

Results

The ECG signals were successfully recorded during the experiment. The HR was significantly decreased during the period of regulation compared with control (-79.3 ±34.5, P < 0.01, n = 6) and then recovered to normal after regulation.

Conclusion

The described implanted chip system can regulate the HR to a designated set point.     

Sequential involvement of the nervous system in subacute combined degeneration

Purpose

Subacute combined degeneration (SCD) involves progressive degeneration of the spinal cord, optic nerve, and peripheral nerves. Vitamin B12 (VB12) is a co-factor in myelin synthesis. Because each cell that constitutes the myelin component in the central nervous system and peripheral nervous system is different, it is improbable that these cells undergo simultaneous degeneration. However, the sequence of degeneration in SCD has not been established.

Materials and Methods

In this study, we analysed medical records and electrophysiological data of patients who showed neurological symptoms and whose serum VB12 levels were lower than 200 pg/mL.

Results

We enrolled 49 patients in this study. Their mean VB12 level was 68.3 pg/mL. Somatosensory evoked potential (SEP) study showed abnormal findings in 38 patients. Of the 40 patients who underwent visual evoked potential (VEP) study, 14 showed abnormal responses. Eighteen patients showed abnormal findings on a nerve conduction study (NCS). In this study, abnormal posterior tibial nerve SEPs only were seen in 16 patients, median nerve SEPs only were seen in 3 patients, abnormal VEPs only in two, and abnormal NCS responses in one patient. No patient complained of cognitive symptoms.

Conclusion

In SCD, degeneration appears to progress in the following order: lower spinal cord, cervical spinal cord, peripheral nerve/optic nerve, and finally, the brain.     

Peripheral vascular surgical procedures in Ilorin, Nigeria: indications and outcome

Background

Data on peripheral vascular surgical interventions from Nigeria is scanty. Reports form Western and Eastern Nigeria dates back about twodecades. This study therefore analyses the various etiological conditions necessitating intervention, and their outcome.

Methods

A retrospective analysis of patients requiring surgical intervention on peripheral vessels from a prospectively collected single surgeon database over a two-year period was conducted. Data were analysed using SPSS version 15.0 windows statistical package.

Results

Fourteen peripheral vascular surgical procedures were performed. The age range was 2–70years (24.4±16.3) with five cases (35.7%) in 20–29year group. Trauma accounted for 11 (73.3%) cases. Upper limb involvement occurred in 7 (63.6%) of the traumatic cases whereas all 2 true aneurysm occurred in the lower limb. Direct repair was possible in re-establishing anatomic continuity in about 64% of cases. Of the six morbidities, wound infection accounted for 50% followed by failure of re-vascularizaton (33.3%) and there was one mortality.

Conclusion

Trauma is the leading cause of peripheral vascular condition necessitating surgery from our study. Young adults predominate. Though direct repair are often feasible, there is a need for the availability of graft options. Wound infection constitutes the highest post-operative morbidity.     

Type 2 diabetes and dog walking: patients' longitudinal perspectives about implementing and sustaining physical activity

Background

Physical activity is particularly important for people with type 2 diabetes, as evidence suggests that any reduction in sedentary time is good for metabolic health.

Aim

To explore type 2 diabetes patients'' talk about implementing and sustaining physical activity.

Design of study

Longitudinal, qualitative study using repeat in-depth interviews with 20 patients over 4 years following clinical diagnosis.

Setting

Patients were recruited from 16 general practices and three hospitals across Lothian, Scotland.

Results

Discussion, and salience, of physical activity was marginal in patient accounts of their diabetes management. Patients claimed to have only received vague and non-specific guidance about physical activity from health professionals, and emphasised a perceived lack of interest and encouragement. Aside from walking, physical activities which were adopted tended to attenuate over time. Patients'' accounts revealed how walking a dog assisted this kind of activity maintenance over time. Three main themes are highlighted in the analysis: 1) incidental walking; 2) incremental physical activity gains; and 3) augmenting physical activity maintenance. The problems arising from walking without a dog (for example, lack of motivation) are also examined.

Conclusion

Asking patients about pet preferences might seem tangential to medical interactions. However, encouraging dog walking or identifying another interest that promotes a regular commitment to undertake physical activity may yield long-term health benefits.     

Different methods for inducing adipose-derived stem cells to differentiate into Schwann-like cells

Introduction

The aim of the study was to explore an effective method to induce adipose-derived stem cells (ADSCs) to differentiate into Schwann-like cells in vitro.

Material and methods

Reagents were applied in two different ways (Dezawa inducing method and modified inducing method) in which inducers including β-mercaptoethanol (β-ME), all-trans-retinoic acid (ATRA), type I collagenase, forskolin, heregulin, basic fibroblast growth factor (BFGF) and brain-derived neurotrophic factor (BDNF) were used in different ways to induce ADSCs of rats to differentiate into Schwann-like cells. After induction, the cell morphologic characteristics and the cellular immunohistochemical staining positive rate of anti-S100 and anti-GFAP (glial fibrillary acidic protein) antibodies and the gray value of immunocytochemical dye with anti-S100 and anti-GFAP antibodies and cell activity measured by the MTT method were compared with each other to evaluate the induction effects.

Results

Both methods can induce differentiation of ADSCs of rats into Schwann-like cells, but the cellular morphology of the modified method was more similar to Schwann cells than that of the Dezawa inducing method, there was a higher cellular immunohistochemical staining positive rate and staining grey value in immunocytochemical dye with anti-S100 and anti-GFAP antibodies, and less damage in the cell activity of the modified inducing method than that of the Dezawa inducing method.

Conclusions

The effect of the modified method to induce ADSCs to differentiate into Schwann-like cells in vitro is superior to that of the Dezawa inducing method.     

Effect of combined single-injection femoral nerve block and patient-controlled epidural analgesia in patients undergoing total knee replacement

Purpose

Total knee replacement is one of the most painful orthopedic procedures, and effective pain relief is essential for early mobility and discharge from hospital. The aim of this study was to evaluate whether addition of single-injection femoral nerve block to epidural analgesia would provide better postoperative pain control, compared to epidural analgesia alone, after total knee replacement.

Materials and Methods

Thirty-eight patients received a single-injection femoral nerve block with 0.25% levobupivacaine (30 mL) combined with epidural analgesia (femoral nerve block group) and 40 patients received epidural analgesia alone (control group). Pain intensity and volume of patient-controlled epidural analgesia medication and rescue analgesic requirements were measured in the first 48 hours after surgery at three time periods; 0-6 hours, 6-24 hours, and 24-48 hours. Also, side effects such as nausea, vomiting, and pruritus were evaluated.

Results

Median visual analog scale at rest and movement was significantly lower until 48 hours in the femoral nerve block group. Patient-controlled epidural analgesia volume was significantly lower throughout the study period, however, rescue analgesia requirements were significantly lower only up to 6 hours in the femoral nerve block group. The incidences of nausea and vomiting and rescue antiemetic requirement were significantly lower in the femoral nerve block group up to 6 hours.

Conclusion

The combination of femoral nerve block with epidural analgesia is an effective pain management regimen in patients undergoing unilateral total knee replacement.     

Treatment of osteochondral injuries with platelet gel

OBJECTIVES:

Treatments for injured articular cartilage have not advanced to the point that efficient regeneration is possible. However, there has been an increase in the use of platelet-rich plasma for the treatment of several orthopedic disorders, including chondral injuries. Our hypothesis is that the treatment of chondral injuries with platelet gel results in higher-quality repair tissue after 180 days compared with chondral injuries not treated with gel.

METHODS:

A controlled experimental laboratory study was performed on 30 male rabbits to evaluate osteochondral injury repair after treatment with or without platelet gel. Osteochondral injuries were surgically induced in both knees of each rabbit at the medial femoral condyle. The left knee injury was filled with the platelet gel, and the right knee was not treated. Microscopic analysis of both knee samples was performed after 180 days using a histological grading scale.

RESULTS:

The only histological evaluation criterion that was not significantly different between treatments was metachromasia. The group that was treated with platelet gel exhibited superior results in all other criteria (cell morphology, surface regularity, chondral thickness and repair tissue integration) and in the total score.

CONCLUSION:

The repair tissue was histologically superior after 180 days in the study group treated with platelet gel compared with the group of untreated injuries.