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PubMed2006

Augmentation of partially regenerated nerves by end-to-side side-to-side grafting neurotization: experience based on eight late obstetric brachial plexus cases.

OBJECTIVE: The effect of end-to-side neurotization of partially regenerated recipient nerves on improving motor power in late obstetric brachial plexus lesions, so-called nerve augmentation, was investigated. METHODS: Eight cases aged 3-7 years were operated upon and followed up for 4 years (C5,6 rupture C7,8 T1 avulsion: 5; C5,6,7,8 rupture T1 avulsion: 1; C5,6,8 T1 rupture C7 avulsion: 1; C5,6,7 rupture C8 T1 compression: one 3 year presentation after former neurotization at 3 months). Grade 1-3 muscles were neurotized. Grade 0 muscles were neurotized, if the electromyogram showed scattered motor unit action potentials on voluntary contraction without interference pattern. Donor nerves included: the phrenic, accessory, descending and ascending loops of the ansa cervicalis, 3rd and 4th intercostals and contralateral C7. RESULTS: Superior proximal to distal regeneration was observed firstly. Differential regeneration of muscles supplied by the same nerve was observed secondly (superior supraspinatus to infraspinatus regeneration). Differential regeneration of antagonistic muscles was observed thirdly (superior biceps to triceps and pronator teres to supinator recovery). Differential regeneration of fibres within the same muscle was observed fourthly (superior anterior and middle to posterior deltoid regeneration). Differential regeneration of muscles having different preoperative motor powers was noted fifthly; improvement to Grade 3 or more occurred more in Grade 2 than in Grade 0 or Grade 1 muscles. Improvements of cocontractions and of shoulder, forearm and wrist deformities were noted sixthly. The shoulder, elbow and hand scores improved in 4 cases. LIMITATIONS: The sample size is small. Controls are necessary to rule out any natural improvement of the lesion. There is intra- and interobserver variability in testing muscle power and cocontractions. CONCLUSION: Nerve augmentation improves cocontractions and muscle power in the biceps, pectoral muscles, supraspinatus, anterior and lateral deltoids, triceps and in Grade 2 or more forearm muscles. As it is less expected to improve infraspinatus power, it should be associated with a humeral derotation osteotomy and tendon transfer. Function to non improving Grade 0 or 1 forearm muscles should be restored by muscle transplantation. LEVEL OF EVIDENCE: Level IV, prospective case series.

Journal Article↗
PubMed2005

Improved muscle healing through enhanced regeneration and reduced fibrosis in myostatin-null mice.

Numerous stimulatory growth factors that can influence muscle regeneration are known. Recently, it has been demonstrated that neutralization of muscle growth inhibitory factors, such as myostatin (Mstn; also known as growth differentiation factor 8, Gdf8), also leads to increased muscle regeneration in mdx mice that are known to have cycles of degeneration. However, the precise mechanism by which Mstn regulates muscle regeneration has not yet been fully determined. To investigate the role of Mstn in adult skeletal muscle regeneration, wild-type and myostatin-null (Mstn-/-) mice were injured with notexin. Forty-eight hours after injury, accelerated migration and enhanced accretion of myogenic cells (MyoD1+) and macrophages (Mac-1+) was observed at the site of regeneration in Mstn-/- muscle as compared with wild-type muscle. Inflammatory cell numbers decreased more rapidly in the Mstn-/- muscle, indicating that the whole process of inflammatory cell response is accelerated in Mstn-/- mice. Consistent with this result, the addition of recombinant Mstn reduced the activation of satellite cells (SCs) and chemotactic movements of both myoblasts and macrophages ex vivo. Examination of regenerated muscle (28 days after injury) also revealed that Mstn-/- mice showed increased expression of decorin mRNA, reduced fibrosis and improved healing as compared with wild-type mice. On the basis of these results, we propose that Mstn negatively regulates muscle regeneration not only by controlling SC activation but also by regulating the migration of myoblasts and macrophages to the site of injury. Thus, antagonists of Mstn could potentially be useful as pharmacological agents for the treatment of disorders of overt degeneration and regeneration.

Animals↗
PubMed2001

Enhanced regeneration of rice (Oryza sativa L.) embryogenic callus by light irradiation in growth phase.

The effect of light irradiation on the growth and regeneration of embryogenic rice calli was investigated. Rice calli grew slightly better in the light than in the dark during the growth stage. When calli subcultured under light irradiation were transferred into a liquid regeneration culture system, the number of plantlets with shoots regenerated from calli subcultured in the light was higher than in the case of those subcultured in the dark, whereas there was no obvious difference between the light and dark subcultures when a solid medium was used for the regeneration. The number of regenerated plantlets increased with increasing light intensity up to 2000 lx, but remained the same when the light intensity was raised further. The maximum number of regenerated plantlets was obtained under a photoperiod of 16 h/d. About 8800 plantlets per liter-medium were regenerated from light-cultured calli, which is 1.5 times more than the number regenerated from calli grown in the conventional dark culture.

Journal Article↗
PubMed2001

Identification of Up-regulated Genes in Rat Regenerating Liver Tissue by Suppression Subtractive Hybridization.

Suppression subtractive hybridization (SSH) technique was used to screen up-regulated genes in regenerating liver. The cDNA from rat regenerating liver tissue was used as the tester, and that from normal liver was used as the driver. After cloning, a subtraction cDNA library of 900 clones was obtained. These 900 clones were further analyzed by differential gene expression screening, and 50 clones with obvious overexpression in regenerating liver were identified. Sequencing analysis and homology searching showed that these clones represent 37 genes, 13 of them are homologous to genes known to be involved in liver regeneration 15 are known genes which are first found to be up-regulated in regenerating liver and 9 are novel genes (ESTs) which have been deposited to GenBank. RNA dot blotting analysis was used to further study the gene expression patterns. The results not only confirmed the up-regulation of these genes in regenerating liver tissue, but also showed that these genes had different expression patterns during the process of liver regeneration. The results implied that these genes might play important roles in liver regeneration.

Journal Article↗
PubMed1998

Complex of Natural Cytokines Regulate Post-Burn Regeneration in Cornea.

Cytokines form a kind of regulatory net which normal functioning is critical for development of inflammation and regeneration in eye, namely cornea. In connection with this, we studied effects of complex of natural cytokine obtained from pig and comprising activities of IL-1, IL-6, TNF, MIF, TGFbeta1, on post-burn regeneration in rabbit cornea. The cornea burn was induced by 10% NaOH and cytokine complex was locally administered (over month after the burn) to the regeneration site observed as wall-eye. Hystologic analysis and in vitro experiment with mice (F1 hybrids of CBAxC57BL) peritoneal macrophages and human peripheral blood neutrophils were performed to reveal cytokine biological roles. CC augmented post-burn cornea regeneration that is distinctly observed at all regeneration stages and manifested as: (i) action on macrophages at the early regeneration (inhibition of migration, activation of phagocytosis, ROS production, cytokine synthesis and secretion); and (ii) attraction of cornea stromal cells to the regeneration site and enhancement of their main functions (proliferation, fibronectin and collagen synthesis). As a consequence of CC local administration, post-burn regeneration site displayed high plasticity, low scaring and vascularization, being close to those of normal tissue, that finally enabled progression of successful keratoplastics. The data reported below show wide perspectives for administration of natural cytokine complex to treat cornea alterations of various genesis.

Journal Article↗
PubMed2006

Optimization of regenerated bone char for fluoride removal in drinking water: a case study in Tanzania.

This paper presents findings of a study on optimization and application of the regenerated bone char media for the defluoridation of drinking water in Tanzania where more than 30% of all water sources have fluoride concentrations above the 1.50 mg/I which is recommended by the World Heath Organization (WHO). In this study, regeneration temperature, regeneration duration, contact time, regenerated bone char dosage and particle size were investigated. Results indicate that the highest fluoride removal and adsorption capacity were 70.64% and 0.75 mg-F/g-bc, respectively, for a sample with bone char material that was regenerated at 500 degrees C. In this study the optimum burning duration was found to be 120 min, which resulted in residual fluoride that varied from a maximum value of 17.43 mg/I for a 2 min contact time to a minimum value of 8.53 mg/I for a contact time of 180 min. This study further indicated that the smallest size of regenerated bone char media (0.5-1.0 mm diameter) had the highest defluoridation capacity, with residual fluoride which varied from 17.82 mg/I at 2 min contact time to 11.26 mg/I at 120 min contact time. In terms of dosage of the regenerated bone char media it was established that the optimum dosage was 25g of bone char media with a grain size of 0.50-1.0 mm. This had a fluoride removal capacity of 0.55 mg-F/g-BC. Column filter experiments indicated that regenerated bone media is capable of removing fluoride from dinking water to meet both WHO and Tanzania recommended values.

Animals↗
PubMed1996

Local and systemic alterations in cyclic 3',5' AMP phosphodiesterase activity in relation to tail regeneration under hypothyroidism and T4 replacement in the lizard, Mabuya carinata.

To establish the relationship between thyroid hormone and cyclic Adenosine monophosphate (cAMP) during lacertilian tail regeneration, cAMP phosphodiesterase, the hydrolytic enzyme of cAMP, was assayed in the tail regenerate, liver, and skeletal muscle of control (group A), chemically thyroidectomized (group B), and thyroidectomized and T4-replaced (group C) animals during various periods of tail regeneration. Enzyme activity was elevated in all three tissues of group B animals. Animals of group C showed an intermediate level of enzyme activity between controls (group A) and experimental animals (group B). These observations suggest a possible regulatory role of thyroxine in maintaining optimum levels of phosphodiesterase. The retardation in regeneration observable in the hypothyroid group of animals may be correlated with low levels of tissue cAMP. However, the operation of other influencing factors on phosphodiesterase during regeneration can be surmised from the observed tendency to exhibit similar patterns of phase-specific modulations in enzyme activity. Our observations are discussed in terms of phase-specific involvement of cAMP in regeneration, as well as its role in other metabolic aspects and the possible mode of indirect control exerted by thyroxine on lacertilian tail regeneration.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1992

Analysis of low affinity nerve growth factor receptor during pulpal healing and regeneration of myelinated and unmyelinated axons in replanted teeth.

Nerve regeneration was examined in rat molars that were briefly extracted and then replanted in the socket for 1-90 days. Immunocytochemistry was used to evaluate neural and nonneural immunoreactivity (IR) for low affinity nerve growth factor receptor (p75-NGFR) and for laminin and calcitonin gene-related peptide (CGRP). Three different types of pulpal response to replantation were found. Type I: Some replanted teeth had mild injury and still contained coronal odontoblasts and associated fibroblasts that retained p75-NGFR-IR; they continued regular dentin formation and had excellent reinnervation. Type II: Teeth with intermediate injury lost most or all of the coronal pulp tissue, but they regenerated odontoblast-like cells that formed irregular dentin, they had numerous dispersed p75-NGFR-IR fibroblasts in crown pulp during early regeneration, and they had excellent reinnervation. Type III: Severely injured teeth lost their original pulp; they filled with dense connective tissue and bone and had poor reinnervation. After Type I or II injury the Schwann cells around degenerating myelinated and unmyelinated axons had increased expression of p75-NGFR by 1-3 days. By 7-10 days those Schwann cells had formed hollow tubes (bands of Bungner) along the degenerating axon tracks. They maintained their increased p75-NGFR-IR during and after regeneration of unmyelinated axons, whereas Schwann cells involved in remyelination lost p75-NGFR-IR at that stage. The number of CGRP-IR axons in the regenerating pulp increased from 7 to 90 days. Laminin-IR increased in all replanted teeth at 3-10 days and only returned to normal patterns in teeth with Type I or Type II response at 20-90 days. The special p75-NGFR-IR of pulpal fibroblasts of adult rat molars did not usually persist in regenerated, reinnervated pulp. The extensive depletion of fibroblast p75-NGFR-IR and the continuing enhanced p75-NGFR-IR in unmyelinated nerve fibers at 90 days show that altered growth factor conditions characterize regenerated pulp of replanted teeth.

Animals↗
PubMed2000

Ultrastructure and innervation of regenerated intrafusal muscle fibres in heterochronous isografts of the fast rat muscle.

Extensor digitorum longus (EDL) muscles from 2- to 28-day-old rats were grafted into EDL muscles of adult inbred recipients (n = 8). At 1-6 months after the operation, experimental muscles were excised and the ultrastructure and innervation of regenerated muscle spindles was examined. Regenerated muscle spindles (n = 36) in isografted EDL muscles contained 4.3 +/- 0.2 (mean +/- SEM) encapsulated muscle fibres. These "intrafusal" muscle fibres lacked nuclear bag and nuclear chain accumulations, which are characteristic of normal muscle spindles; thus, they rather resembled thin encapsulated extrafusal muscle fibres. In the same sample, myelinated axons were found in 33 (92%) muscle spindles, but no sensory terminals were found. These findings demonstrate that regenerated spindles in isografted EDL muscles were not reinnervated by spindle-specific sensory axons, but exclusively by motor axons. Typical intracapsular motor endplates (MEPs) were found in one third of regenerated spindles examined. Their motor terminals contained accumulated mitochondria and synaptic vesicles. As is characteristic for MEPs, axolemma and sarcolemma were separated by a synaptic cleft about 60 nm wide that contained a basal lamina. The underlying sarcolemma formed either small infoldings or none at all, and the subsynaptic area contained only small subsarcolemmal accumulations of mitochondria. It is apparent that the structures described here as "regenerated muscle spindles" do not perform their normal physiological function as stretch receptors because they lack the sensory innervation. The present results show that regeneration and reinnervation in heterochronous isografts corresponds to that previously described in autotransplanted free muscle grafts. The results also show that, during muscle spindle regeneration, intrafusal satellite cells develop into extrafusal-like muscle fibres, apparently due to their motor innervation.

Animals↗
PubMed1991

Myosin isoform transitions and physiological properties of regenerated and re-innervated soleus muscles of the rat.

Soleus muscles in young female rats were destroyed by the local injection of the crude venom of the Australian tiger snake, Notechis scutatus and allowed to regenerate. The regenerated muscles consisted almost exclusively of type I muscle fibres, and histograms of fibre cross-sectional area were unimodal. In contrast the normal contralateral muscles consisted of a mixture of type I and IIa fibres, and histograms of fibre cross-sectional area were bimodal. There was no change in the ability of the regenerated muscles to generate tension in response to indirect stimulation, and muscle fibre number and motor unit index were similar to controls. The regenerated muscles often contained split muscle fibres, but if re-innervation of the regenerated muscles was delayed, splitting did not occur. The principal features of the regenerated muscles (fibre type homogeneity, unimodal histograms of muscle fibre area, normal numbers of muscle fibres and normal motor unit index) were reproduced in soleus muscles that were simply denervated by nerve crush and allowed to re-innervate. We conclude that the phenotypic homogeneity of the regenerated muscles is a consequence of the temporary disconnection of muscle from nerve, rather than of the cycle of degeneration/regeneration, and suggest that this disconnection results in the reprogramming of the soleus motor neurones.

Animals↗
PubMed2005

Long term assessment of axonal regeneration through polyimide regenerative electrodes to interface the peripheral nerve.

Polyimide sieve electrodes were implanted between the severed ends of the sciatic nerve in rats. The degree of axonal regeneration through the electrode was examined by physiological and histological methods from 2 to 12 months postimplantation. Regeneration was successful in the 30 animals implanted. Functional reinnervation of hindlimb targets progressed to reach maximal levels at 6 months. Comparatively, the reinnervation of distal plantar muscles was lower than that of proximal muscles and of digital nerves. The number of regenerated myelinated fibers increased from 2 to 6 months, when it was similar to control values. The majority of myelinated fibers crossing the via holes and regenerated through the distal nerve had a normal appearance. However, in a few cases decline of target reinnervation and loss of regenerated nerve fibers was found from 6 to 12 months postimplantation. Motor axons labeled by ChAT immunoreactivity regenerated scattered within minifascicles, although they were found at higher density at the periphery of the regenerated nerve. The number of ChAT-positive axons was markedly lower distally than proximally to the sieve electrode.

Action Potentials↗
PubMed2001

Expression of growth-factor receptors in normal and regenerating human periodontal cells.

Growth factors are biologically active mediators that bind to specific receptors on target cells and regulate genes involved in cell growth, wound healing and regeneration. The expression of these receptors is thus of fundamental importance for the response of the cells to the factors. The aim here was to examine, using immunohistochemistry and flow cytometry, the expression of growth factor receptors in normal gingiva, periodontal ligament and in cells derived from these tissues, and also in regenerated tissues following guided tissue regeneration (GTR). By immunocytochemistry platelet-derived growth factor receptor-alpha (PDGF-Ralpha) was not detected in any of the tissues, whereas the PDGF-Rbeta and transforming growth factor-beta receptor types I and II (TGF-beta RI, RII) appeared to be upregulated in regenerated tissues compared with gingival and periodontal ligament tissues. Epidermal growth factor receptor (EGF-R) was also notably elevated in the regenerated tissue and was strongly expressed in the gingival epithelium but not in the periodontal ligament. Neither were fibroblast growth factor receptor-I (FGF-RI) or insulin-like growth factor receptor (IGF-R) detected in the periodontal ligament, nor in the gingiva, but they sometimes stained weakly in the regenerated tissues. Flow cytometry (FCM) showed that all the cells derived from the normal gingiva and the periodontal ligament expressed the PDGF-Rbeta, whereas the TGF-beta RI and RII, FGF-RI and IGF-R were detected in only a proportion of the total cells. In contrast, none of the cells expressed the PDGF-Ralpha or the EGF-R. These observations show that the growth factor receptors are differentially expressed by the periodontal tissues and cells and suggest that the corresponding factors may also be differentially involved in periodontal wound healing and regeneration.

Epithelium↗
PubMed1998

Regeneration of implanted splenic tissue in the rat: re-innervation is host age-dependent and necessary for tissue development.

The loss of spleen may lead to fatal bacterial infections. To prevent this, splenic autotransplantation has been performed in humans and experimental animals. However, there is still controversy about the protective function of this procedure. Since innervation plays an important role in splenic function, we investigated whether splenic regenerates are re-innervated, and whether this depends on the donor and host age. Splenic tissue (30 mg) was implanted into the greater omentum of either young (2 days) or old (12 months) rats, from either young or old syngeneic animals. After 3 months of regeneration, the weight of the regenerates was determined, PGP+ nerve fibers were revealed by immunohistology, and subdivided into nerve fibers of sympathetic (TH+, NPY+) or sensory (SP+, CGRP+) origin. In addition, proliferating (Ki-67 proliferation antigen+) and apoptotic cells (TUNEL technique+) were likewise investigated. No innervation of splenic regenerates was observed after implantation into old hosts, correlating with poorly developed splenic compartments. In contrast, almost normal re-innervation occurred in young hosts after implantation of both young and old splenic tissue. These regenerates showed well-developed splenic compartments and a normal number and tissue distribution of proliferating and apoptotic cells. However, after the implantation of young tissue, the final size of splenic regenerates was three times larger (140 +/- 30 vs. 40 +/- 10 mg). Thus, re-innervation of splenic implants is necessary for their subsequent development. It is determined by host age, whereas the final size of the splenic regenerates is regulated by donor age-dependent factors. This model is useful for studying both the process leading to initial innervation and the consequences of this innervation.

Aging↗
PubMed2003

Periodontal repair in dogs: rhBMP-2 significantly enhances bone formation under provisions for guided tissue regeneration.

BACKGROUND: Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been shown to support the regeneration of alveolar bone and periodontal attachment in surgically created periodontal defects and in defects with a history of dental plaque and calculus exposure. Periodontal regeneration has also been shown following guided tissue regeneration using space-providing expanded polytetrafluoroethylene (ePTFE) devices. The objective of this study was to evaluate the influence of rhBMP-2 on regeneration of alveolar bone and periodontal attachment used in conjunction with a space-providing ePTFE device. METHODS: Routine, critical-size, 5-6 mm, supra-alveolar, periodontal defects were created around the third and fourth mandibular premolar teeth in four young adult Hound Labrador mongrel dogs. rhBMP-2 (0.2 mg/ml) in an absorbable collagen sponge (rhBMP-2/ACS) or buffer/ACS (control) implants were randomly assigned to be placed around the premolar teeth in the left and right jaw quadrants in subsequent animals. Space-providing ePTFE devices with 300-microm laser-drilled pores, 0.8 mm apart, were used to cover the rhBMP-2 and control implants. The gingival flaps were advanced for primary wound closure. The animals were euthanized at 8 weeks postsurgery for histologic and histometric analyses. RESULTS: Bone regeneration and ankylosis were significantly increased in jaw quadrants receiving rhBMP-2/ACS compared to control (bone height 4.8+/-0.3 versus 2.0+/-0.2 mm, p=0.001; bone area 10.9+/-1.3 versus 1.4+/-0.1 mm2; p=0.009, and ankylosis 2.2+/-0.2 versus 0.04+/-0.7 mm; p=0.01). No differences between groups were found for cementum regeneration and root resorption. CONCLUSIONS: rhBMP-2 significantly enhances regeneration of alveolar bone in conjunction with a space-providing, macroporous ePTFE device for GTR.

Alveolar Bone Loss↗
PubMed2002

A systematic review of the survival of implants in bone sites augmented with barrier membranes (guided bone regeneration) in partially edentulous patients.

The aim of the present systematic review was to assess the survival of implants in regenerated bone applying the method of guided bone regeneration (GBR) compared with the survival of implants in non-regenerated bone. Studies to be included in this review needed to provide at least 12-month results following prosthetic reconstruction of titanium implants in bone regenerated by GBR with or without membrane supporting materials. The outcome measures were implant survival described as presence of implant, implant success (according to the criteria in the respective study), absence of clinical implant mobility, absence of implant fracture, absence of progressive peri-implant crestal bone loss as assessed on radiographs without clinical signs of peri-implant infection, absence of peri-implant infection with suppuration. A MEDLINE search and a hand search of relevant scientific journals were conducted including studies from the year 1990 to May 2001. A total of 11 studies could be identified fulfilling the inclusion criteria. All studies except two had the characteristics of case series or cross-sectional surveys. The two different studies had both test and control implants included in their analysis and qualified as controlled clinical trials. Cumulative success or survival rates, respectively, for implants in regenerated bone ranged from 100% after 5 years to 79.4% after 5 years of function. Regarding survival data, no significant differences were found in the controlled clinical trials between implants in regenerated compared to implants in non-regenerated bone. Within the limits of this systematic review characterized by second and third levels of evidence, the following conclusions can be drawn: The survival rate of implants placed into sites with regenerated/augmented bone using barrier membranes varied between 79% and 100% with the majority of studies indicating more than 90% after at least one year of function. The survival rates obtained in the present systematic review are similar to those generally reported for implants placed conventionally into sites without the need for bone augmentation.

Adult↗
PubMed1994

Regeneration of junctional epithelium and its innervation in adult rats: a study using immunocytochemistry for p75 nerve growth factor receptor and calcitonin gene-related peptide.

Junctional epithelium (JE) is a rapidly proliferating tissue that connects the gum to the tooth, that provides a free surface for bidirectional movement of substances between the body and the oral cavity, and that participates in defense against bacterial infection. It is innervated by numerous sensory nerve fibers that are immunoreactive (IR) for neuropeptides such as calcitonin gene-related peptide (CGRP), and for low affinity nerve growth factor receptor (p75-NGFR). Basal epithelial cells of the JE and of adjacent sulcular epithelium also have intense p75-NGFR-IR. In the present study we removed a wedge of the free gingiva and JE from the anterior side of the maxillary first molar of adult rats, and then studied the return of nerve fibers during tissue regeneration from 1-63 days after gingivectomy. The nerve fibers entered the adjacent healing sulcular epithelium before innervating the new JE, in both cases prior to return of epithelial cell p75-NGFR-IR. The regenerating nerve fibers completely bypassed the zone of epithelial down-growth (long junctional epithelium, LJE) that was briefly present along the tooth from 1-3 weeks after injury. The LJE did not have p75-NGFR-IR and was gradually replaced by a modified thicker regenerated junctional epithelium (RJE). The RJE was attached along the injured root surface, had numerous nerves in basal layers, and it had begun to regain p75-NGFR-IR staining of basal epithelial cells by 22 d. Regenerating nerve fibers at 6-10 d had unusually weak CGRP-IR and greatly increased p75-NGFR-IR. Both nerve stains had returned to normal by 3-6 weeks. The intense p75-NGFR-IR of regenerating nerves was found on both axonal and Schwann cell membranes using electron microscopic immunocytochemistry. In both the normal and regenerating JE, nerve fibers were rare in the attachment layers next to the anterior side of the maxillary first molar, compared to well-innervated basal layers. The complete avoidance of LJE by regenerating nerve fibers and its lack of p75-NGFR-IR suggest that its functions do not require innervation and that it does not make neurotrophic growth factors.

Animals↗
PubMed1987

The nerve dependence of amphibian limb regeneration.

The regeneration of limbs in urodele amphibians is a context where the developing and regenerating peripheral nervous system interacts with the mechanisms of epimorphic regeneration. After amputation of a limb, there arise at the amputation plane the blastemal cells which are the progenitor cells of the regenerate. These cells divide rapidly and subsequently differentiate to give rise to the internal tissues (cartilage, muscle and connective tissue) of the regenerate. Division of the blastemal cells requires the presence of nerve axons at the amputation plane, at least during the initial stages of regeneration. This requirement can be circumvented by allowing a limb to develop in the absence of a nerve supply (the 'aneurogenic limb'), but the underlying mechanisms have been unclear. We have derived a monoclonal antibody called 22/18 that has provided new information about these issues. It is specific for blastemal cells versus normal tissue in the limb, specific for regeneration versus development, and specific for blastemal cells that arise after amputation in the presence of the nervous system versus its absence (in either development or the aneurogenic limb). The antibody reactivity appears to mark a cell transition involved in the imposition of nerve-dependent growth control.

Animals↗
PubMed2001

Hydrobia ulvae (Gastropoda: Prosobranchia): a new model for regeneration studies.

Within 2 weeks of decapitation, Hydrobia ulvae was able to regenerate new head structures including buccal ganglia. It was also capable of regenerating propodial ganglia after anterior foot amputation. The functional regeneration of the buccal ganglia was demonstrated by behavioural observations and by electrophysiological experiments. The presence of the oesophagus was shown to be important for regeneration of the buccal complex. H. ulvae provides a new model for regeneration studies, so details of the topographic anatomy and biology of this species are described. To standardize experimental animals in future studies, the effects of age, sex and trematode infestation on the regeneration capacity of H. ulvae have been evaluated. The high capacity for regeneration together with the possibility of using electrophysiological techniques makes H. ulvae a favourable model in which to study neurogenesis in adult animals.

Animals↗