Degenerative joint disease in Praomys (Mastomys) natalensis

Cell-based therapy for disc repair

BACKGROUND CONTEXT

One of the most promising therapies for symptomatic disc degeneration involves the implantation of therapeutic cells into the degenerative disc.

PURPOSE

In this article, the rationale and approaches for cell-based tissue engineering of the intervertebral disc are discussed.

STUDY DESIGN

The scientific literature related to cell-based tissue engineering of the intervertebral disc is reviewed.

METHODS

A variety of cell types have been used in various research models to affect matrix repair of the intervertebral disc. The use of cellular scaffolds and growth factors or genes also appears promising for achieving meaningful tissue repair of the intervertebral disc.

RESULTS

Disc tissue engineering is a promising approach for achieving repair of the intervertebral disc. Using cell-based approaches, various research models suggest that improvements in the complex matrix of the disc may be achieved.

CONCLUSION

A cell-based approach to repair of the intervertebral disc appears promising. More research is needed to define the optimal cell type, cellular scaffold and mixture of growth factors that may allow meaningful repair of the human symptomatic degenerative disc.

Isolated Acromioclavicular Joint Pathology in the Symptomatic Shoulder on Magnetic Resonance Imaging

The acromioclavicular (AC) joint is a synovial joint that is predisposed to painful syndromes because of mechanical stress or developmental variation. It is often overlooked in the evaluation of patients with shoulder pain, however. Isolated AC joint pathology was studied on magnetic resonance imaging scans of patients with symptoms suggesting rotator cuff pathology. The conditions identified included osteoarthritis, distal clavicle osteolysis, and os acromiale syndrome.

A fibronectin fragment stimulates intervertebral disc degeneration in vivo

STUDY DESIGN

A radiographic, histologic, biochemical, and gene expression study was conducted in vivo in a rabbit model to determine the effect of injection of the N-terminal 30 kDa fibronectin fragment (Fn-f) into the intervertebral disc along with various control substances.

OBJECTIVE

To determine if the Fn-f is able to induce disc degeneration in vivo.

SUMMARY OF BACKGROUND DATA

Animal models of disc degeneration are crucial to defining the molecular events involved in disc degeneration. Although spontaneous and induced models of disc degeneration have been described, none is ideal for molecular studies. A better understanding of disc degeneration at the molecular level is necessary to promote rational design of therapies for degenerative disc disease.

MATERIALS AND METHODS

Thirty-one New Zealand white rabbits underwent injection of Fn-f and control substances into the central region of separate lumbar discs using a fine needle. Euthanasia was performed at the 2-, 4-, 8-, 12-, and 16-week time points and the discs were examined radiographically, histologically, biochemically, and with gene expression.

RESULTS

Radiographs demonstrated anterior osteophyte formation at Fn-f-injected disc spaces by the 12-week time point. Histology demonstrated a progressive loss of the normal architecture of the nucleus pulposus and anulus fibrosus over the 16-week study period. A progressive loss of proteoglycans was documented using GAG assay but total collagen did not appear to change appreciably. Gene expression studies demonstrated a significant down-regulation of both aggrecan and type II collagen mRNA between the 8- and 16-week time points.

CONCLUSION

Fn-f appears to induce a progressive degenerative process within the intervertebral disc after injection that resembles degenerative disc disease. This model has several significant advantages for the study of disc degeneration at the molecular level. Further studies are warranted to elucidate the mechanism and molecular events associated with Fn-f-mediated disc degeneration.

Spondylosis in sand rats: a model of intervertebral disc degeneration and hyperostosis

This study defines gross, histopathologic, and radiologic changes associated with intervertebral disc degeneration in a spontaneously occurring form of the disease in aging sand rats (Psammomys obesus). Sand rats (male/female) fed lab chow supplemented with desert salt bush were sacrificed at periods of 3-30 months. Lateral thoracolumbar spine films were obtained. At sacrifice, spines were surgically exposed and gross findings were recorded; after fixation/decalcification, histopathologic studies were carried out using hematoxylin and eosin, and Safranin-O with fast green counterstain. Metabolic studies included correlations of pathologic and radiologic findings with blood glucose and insulin levels. Disc-space narrowing and subchondral endplate sclerosis increased radiologically with age, with more severe lower lumbar disc lesions. Ligamentous calcifications ventral to involved discs and caudal vertebrae were common. Disc thinning and anterior vertebral bony/cartilaginous spurs were more marked with age. Microscopy revealed loss of nucleus pulposus physaliform cells, chondrocyte replication, disc necrosis, and ossification. Hyperglycemia with and without hyperinsulinemia was common. No statistically significant differences in pathologic findings were noted, neither in diabetic versus nondiabetic nor in hyperinsulinemic animals. The sand rat is a model of disc degeneration; similarities with possible overlap with diffuse idiopathic skeletal hyperostosis syndrome were noted.

Spontaneous degenerative spinal disease in the laboratory rabbit

The spines of 35 rabbits (32 New Zealand white and 3 AC/J), ranging in age from 3 months to 8 1/2 years, were investigated systematically for spontaneous degenerative changes. Three types of lesion were observed. (1) The nucleus pulposus underwent chondroid metaplasia throughout the length of the vertebral column by the age of 2 years. (2) Hydroxyapatite deposition was found in the nucleus pulposus in 12 of 20 animals examined roentgenographically. The lesion occurred principally in the distal thoracic segments and was first observed in 3-month-old rabbits. (3) Spondylosis occurred in each of four macerated spines from animals greater than 24 months old. Portions of the spine spared by disc calcification were affected.

Early onset of disk degeneration and spondylosis in sand rats (Psammomys obesus)

The sand rat is a desert animal which feeds mainly on salt bush, a shrub with a high salt content in its leaves. Sand rats have been used for the study of renal function, and since they may develop diabetes if kept on a laboratory diet without a supplement of salt bush, they have been used for investigation of diabetes-related disorders as well. Older diabetic and non-diabetic sand rats are prone to develop severe degeneration of the intervertebral disks, disk herniation, and subsequent hyperostotic spondylosis. This report is concerned with the relation of these processes to aging. The vertebral columns of 25 sand rats which were fed a standard laboratory diet and a supplement of salt bush ad libitum were examined. The sand rats ranged from 12 to 18 months of age. The vertebral columns were dissected, prepared for microscopic examination, and the findings were compared with those obtained previously in sand rats from 1 1/2 to 2 1/2 years of age. Both disk degeneration and spondylosis were comparable in course and frequency to the changes found in the older sand rats. It was concluded that factors other than age are involved in the pathogenesis of disk degeneration in the sand rat.

An electrophoretic polymorphism in the serum transferrins of Praomys (Mastomys) natalensis

Three serum transferrin phenotypes of Praomys (Mastomys) natalensis, and African rodent having a high incidence of many varieties of spontaneous neoplasms, were detected by electrophoresis and autoradiography. On electrophoresis, transferrin of Trf-K was found to be a protein that migrates slowly toward the cathode, whereas that of Trf-M migrates rapidly. Trf-KM is a heterozygous phenotype of the above two. Progeny testing demonstrated that these three serum transferrin phenotypes in Mastomys are probably controlled by two codominant allelic genes, Trfk and Trfm, at a single autosomal locus. The genotypes of these phenotypes may be Trfk/Trfk, Trfm/Trfm, and Trfk/Trfm.

Degenerative myelopathy in three strains of aging rats

Spontaneous paresis and paralysis associated with degenerative spinal cord and spinal nerve root lesions occurred in three strains of rats used in studies of aging. Focal or segmental spinal cord lesions had mild to severe demyelination, loss of nerve axons, and lipid-filled gitter cells. The lesions were limited to the white matter and were most severe in the lateral and ventral funiculi. The nerve roots had cholesterol clefts, focal hemorrhage, and demyelination. Atrophy of the skeletal muscle probably was secondary to the cord lesions. Vertebral lesions that involved the spinal canal and vascular blood flow were found, which may explain pathogenesis.

Spontaneous diseases in a closed colony of Praomys (Mastomys) natalensis

In comparison with other rodents, the mastomys is unique as regards the patterns of neoplastic and non-neoplastic diseases that it develops, some of which may constitute suitable animal models for corresponding diseases of man. Among the spontaneous diseases commonly encountered in necropsies of 600 mastomys maintained in a closed colony were: (1) degenerative joint disease of diarthroses and interventricular disks, which develops regularly in the second year of life; (2) renal disease, a type of immune-complex glomerulonephritis, affecting approximately 80% of mastomys in the age bracket 18-36 months; (3) thymomas and thymic hyperplasia affecting 30% of mastomys by the time they are 2 years old or older; (4) a combination of thymoma and polymyositis in a mastomys showing serum-globulin reactivity, presumably auto-antibody against striated muscle; (5) beginning before the age of 1 year, replacement of the normal cell population of the lymphoid tissues by plasma cells, and intense plasma cell infiltration at many other organ and tissue sites; (6) haematopoietic neoplasms, without leukaemic blood, in 10% of mastomys; and (7) histamine-producing argyrophilic carcinoid tumours of the glandular stomach in approximately 60% of old male and 30% of old female mastomys. Additionally, other neoplasms not infrequently encountered in mastomys rarely occur in other rodent species; conversely some neoplasms commonly found in other rodents, including especially tumours of the lung and mammary gland and leukaemia, are rare or absent in mastomys.

Lassa virus infection in Mastomys natalensis in Sierra Leone. Gross and microscopic findings in infected and uninfected animals

Pathological examinations of 28 wild-caught Mastomys natalensis from Sierra Leone, 14 of which were positive for Lassa virus by tissue culture, are reported. The high frequency of neoplastic and degenerative diseases observed among older animals in closed colonies of M. natalensis were not observed in the wild animals studied. This is probably a reflection of the age distribution of the study population, since the life expectancy of wild Mastomys is less than a year. Inflammatory lesions were nonetheless identified, some of which were similar to those described in laboratory colonies. Frequent lesions were myocarditis (54%), myositis (32%), interstitial pneumonitis (50%), intercapillary glomerulosclerosis (36%), and acute nephrosis (14%). Follicular and nodular lymphoid hyperplasia were evident in the spleen (74%) and Peyer's patches (64%). Lymphoid cell accumulations were prominent in the salivary glands (36%), periportal hepatic region (25%), lungs (32%), perivascular regions (36%), and kidney (21%). Cytomegalic inclusion body sialoadenitis was common (25%). Coccidiosis was evident in the intestinal tract (25%), kidney (25%), and muscle (21%). One neoplasm, a parahepatic haemangioma, was observed histologically.Mean body weights and lengths for virus-positive animals (33 g and 9.2 cm) and virus-negative animals (54 g and 12.2 cm) showed that virus-positive animals were smaller in weight and shorter in length. Since the age of the animals could not be determined, these differences remain unexplained.In comparison with virus-negative animals, virus-positive Mastomys had higher frequencies of splenic follicular hyperplasia (82% against 50%), myocarditis (79% against 29%), perivascular lymphoid cell accumulation (57% against 7%), myositis (50% against 14%), and cytomegalic inclusion body sialoadenitis (36% against 14%). The frequency of lymphoid hyperplasia of Peyer's patches was high in both groups of animals (71% and 57%).The presence of Lassa virus, small size, myocarditis, and lymphoid perivasculitis appeared to be interrelated, but larger and better controlled studies are required to elucidate the relationship.

Histamine production by transplantable argyrophilic gastric carcinoid of Praomys (Mastomys) natalensis

A transplantable argyrophilic gastric carcinoid of Praomys (Mastomys) natalensis contained appreciable amounts of histamine. Dialyzed, microsome-free supernatant of tumor tissue produced definite amounts of histamine in the presence of L-histidine and pyridoxal phosphate. These findings may relate to hypersecretion of gastric acid and formation of multiple ulcers in the stomach and duodenum of Mastomys bearing carcinoids.