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Biomedical subjects

T A Partridge

Publications and source records attributed to T A Partridge.

At least 55 records · Page 3Linked to original sources
PubMed1991

Allografts of muscle precursor cells persist in the non-tolerized host.

Implantation of normal muscle precursor cells into myopathic fibres to alleviate recessively inherited diseases of skeletal muscle has received much attention since the discovery of a defective or deficient gene coding for the protein dystrophin in the Duchenne and Becker forms of muscular dystrophy. Therapeutic allografting of cells would require some means of preventing their immune rejection. Here we have allografted muscle into the non-tolerant and non-immunosuppressed murine host. Precursor cells introduced in the form of a single cell suspension survive for prolonged periods post-implantation. Allografts of minced muscle often failed to survive, even though host and donor were compatible at the major histocompatibility locus. Differences at minor loci may well have contributed to such rejection. Where allografted tissue was rejected, there was a decrease in the amount of surviving host muscle at the graft site, an important observation in terms of the therapeutic implantation of cells.

Animals↗
PubMed1990

Acquisition of a lysosomal enzyme by myoblasts in tissue culture.

Skeletal muscle myoblasts from different sources acquired high levels of the lysosomal enzyme beta-glucuronidase, when they were cultured together with mitogen-activated lymphocytes. Immunofluorescent staining, thermal stability, and electrophoretic mobility showed that the increase in enzyme activity in the myoblasts was due to the presence of the lymphocyte form of the enzyme. Although myoblasts were able to take up exogenous beta-glucuronidase from the culture medium by mannose 6-phosphate receptor-mediated endocytosis, enzyme acquisition during co-culture with lymphocytes was independent of this pathway. Enzyme transfer from the lymphocytes was found to require direct cell-cell contact with the muscle cells, and was accompanied by an increase in beta-glucuronidase activity in the lymphocytes themselves. Since this additional activity was also due to the presence of the lymphocyte form of the enzyme, these results indicate that interaction with the muscle cells induced the de novo synthesis of beta-glucuronidase in the lymphocytes.

Animals↗
PubMed1990

Somatic reversion/suppression of the mouse mdx phenotype in vivo.

The mdx mouse has a myopathy caused by dystrophin deficiency, and is therefore biochemically and genetically homologous to human Duchenne muscular dystrophy. While mdx mouse muscle shows no dystrophin by immunoblotting, a very small percentage of myofibers appear clearly dystrophin-positive by immunofluorescence microscopy. We have characterized these rare positive-staining fibers, and conclude that they are indeed expressing dystrophin despite a nonsense mutation within the dystrophin gene. Thus, the dystrophin-positive fibers probably represent somatic reversion or suppression of the mdx mutation. Cardiac muscle and skeletal muscle from mdx mice showed dramatically different patterns of dystrophin-positive cells. However, this difference is expected given the apparent clonal nature of the reversion/suppression events, the inability of cardiac muscle to regenerate, and other differences in the developmental programs of myofibers and cardiocytes. The prevalence of dystrophin-positive cells in mdx cardiac muscle was determined to be approximately 2 x 10(-5). The observed prevalence of dystrophin-positive cardiocytes in the mdx mouse is a possible estimate of the somatic reversion rate of the mdx mutation in vivo.

Animals↗
PubMed1990

Normal myogenic cells from newborn mice restore normal histology to degenerating muscles of the mdx mouse.

Dystrophin deficiency in skeletal muscle of the x-linked dystrophic (mdx) mouse can be partially remedied by implantation of normal muscle precursor cells (mpc) (Partridge, T. A., J. E. Morgan, G. R. Coulton, E. P. Hoffman, and L. M. Kunkel. 1989. Nature (Lond.). 337:176-179). However, it is difficult to determine whether this biochemical "rescue" results in any improvement in the structure or function of the treated muscle, because the vigorous regeneration of mdx muscle more than compensates for the degeneration (Coulton, G. R., N. A. Curtin, J. E. Morgan, and T. A. Partridge. 1988. Neuropathol. Appl. Neurobiol. 14:299-314). By using x-ray irradiation to prevent mpc proliferation, it is possible to study loss of mdx muscle fibers without the complicating effect of simultaneous fiber regeneration. Thus, improvements in fiber survival resulting from any potential therapy can be detected easily (Wakeford, S., D. J. Watt, and T. A. Patridge. 1990. Muscle & Nerve.) Here, we have implanted normal mpc, obtained from newborn mice, into such preirradiated mdx muscles, finding that it is far more extensively permeated and replaced by implanted mpc than is nonirradiated mdx muscle; this is evident both from analysis of glucose-6-phosphate isomerase isoenzyme markers and from immunoblots and immunostaining of dystrophin in the treated muscles. Incorporation of normal mpc markedly reduces the loss of muscle fibers and the deterioration of muscle structure which otherwise occurs in irradiated mdx muscles. Surprisingly, the regenerated fibers are largely peripherally nucleated, whereas regenerated mouse skeletal muscle fibers are normally centrally nucleated. We attribute this regeneration of apparently normal muscle to the tendency of newborn mouse mpc to recapitulate their neonatal ontogeny, even when grafted into 3-wk-old degenerating muscle.

Animals↗
PubMed1989

Conversion of mdx myofibres from dystrophin-negative to -positive by injection of normal myoblasts.

An important corollary to the recent advances in our understanding of the primary cause of Duchenne muscular dystrophy, is the validation of genuine genetic homologues as animal models of the disease in which potential therapies can be tested. The persistent skeletal muscle necrosis that characterizes human Duchenne muscular dystrophy is also seen in the mdx mouse and is, in both, a consequence of a deficiency of dystrophin, probably within the muscle fibres themselves. As injected muscle precursor cells of one genotype can fuse with host muscle fibres of a different genotype and express the donor genes, we decided to test grafts of normal muscle precursor cells to see if they could induce synthesis of dystrophin in innately dystrophin-deficient mdx muscle fibres. We show that injected normal muscle precursor cells can fuse with pre-existing or regenerating mdx muscle fibres to render many of these fibres dystrophin-positive and so to partially or wholly rescue them from their biochemical defect.

Animals↗
PubMed1989

Mdx muscle grafts retain the mdx phenotype in normal hosts.

Whole muscle grafts were made between mdx and normal mice to investigate whether the mdx myopathic lesion is intrinsic to mdx muscle or is a property of its environment. Grafts were examined between 20 and 101 days. Unequivocal necrotic muscle fibers and/or newly formed basophilic myotubes were noted in 8 of 16 grafts of mdx muscle made in normal hosts but in none of 16 grafts of normal muscle made in mdx hosts. In older grafts, the proportion of centrally nucleated fibers and variability of fiber diameter were both higher in mdx muscle grafted into normal hosts than in normal muscle grafted into either mdx or normal hosts. Analysis of the glucose-6-phosphate isomerase (GPI) isoenzyme content of the grafts indicated that the muscle formed was predominantly of donor origin. These findings provide evidence that the mdx lesion is a primary myopathy rather than secondary to an extramuscular primary lesion.

Animals↗
PubMed1988

Emphysema in the Blotchy mouse: a morphometric study.

Inheritance of the Blotchy allele at the X-chromosomal Mottled locus of mice results in changes in the lung which resemble emphysema. Previous studies using measurements of mean linear intercept have recognized emphysema in the hemizygous, Blo/Y, male and homozygous, Blo/Blo, female, but not in the heterozygous, Blo/+, female. The aim of this study was to develop a rapid, accurate method for analysis of emphysema and to establish whether it would identify emphysema in the heterozygote. Lungs from wild type and outbred Blo mice were inflated with fixative at a pressure of 25 cm and then sectioned and stained. Transect lengths across air spaces were measured using computerized image analysis and the results were plotted as histograms. Data were also expressed as cumulative frequencies (ogives) and subjected to statistical analysis by the non-parametric Kolmogorov-Smirnov test. Emphysema was shown by significantly increased (P less than 0.001) transect lengths in the Blo/Blo female and Blo/Y male compared with the wild type controls. The heterozygous Blo/+ mice form an intermediate group significantly different (P less than 0.001) from the wild and blotchy mice. The sensitivity of the method is illustrated by the fact that the Blo/+ female formed an intermediate group between wild type and the Blo/Y male and Blo/Blo female.

Animals↗
PubMed1988

Partial correction of an inherited biochemical defect of skeletal muscle by grafts of normal muscle precursor cells.

We have attempted to use allografts of normal muscle precursor cells (mpc) to insert donor nuclei, containing a normal genome, into growing or regenerating skeletal muscle fibres of mice with an inherited deficiency of the enzyme phosphorylase kinase (PhK). Analysis of the glucose-6-phosphate isomerase (GPI) isoenzymes of treated muscles showed that myonuclei of donor origin became incorporated into host muscle fibres in 8 of 9 regenerating autografts, but PhK activity was found only in the 3 grafts into which the largest numbers (1-3 x 10(6)) of mpc had been implanted. Following injection of normal mpc into growing PhK-deficient skeletal muscle, mosaic fibres containing myonuclei of donor origin were detected in only 11 of 192 muscles examined from 64 mice, but, of these 11 muscles, 5 contained PhK activity detectable by two separate assays in a further 4 muscles activity was detected by one or other assay.

Animals↗
PubMed1988

Representative sample of rheumatoid synovium: a morphometric study.

The synovium from 11 patients with rheumatoid arthritis, who were undergoing joint surgery, was assessed using histological and morphometric techniques. Histological examination confirmed previous reports that the intensity of the cellular reaction varied throughout the synovium, and the morphometric method reflected this variability sensitively. The method was shown to be reproducible and allowed areas of similar cellular density to be defined. From these defined areas a total of 2.5 mm2 of synovium equivalent to 12 fields at x250 required analysis to reflect the variation in the cellular reaction. It would be feasible to collect this amount of material using an arthroscope.

Arthritis, Rheumatoid↗
PubMed1988

Morphometric comparison of synovium from patients with osteoarthritis and rheumatoid arthritis.

Synovium was collected from 15 patients who were undergoing joint surgery. Two groups were defined by clinical diagnosis: patients with primary osteoarthritis (n = 4); and those with rheumatoid arthritis (n = 11). The synovium was studied using histological and morphometric techniques. In agreement with previous studies, no histological features specific for either diagnosis were found. A previously validated morphometric method was used to estimate the cellular density of randomly picked fields within defined areas of synovium. The mean nuclear density of cellularity of comparable areas of synovium was significantly different between these two disease states, but the mean nuclear density between individual representative samples within each clinical group was homogeneous. The morphometric analysis of lymphocyte subsets showed that within the upper synovial region and cellular aggregates in osteoarthritis, the distribution of T cells expressing the CD4 and CD8 antigen was the same. In rheumatoid arthritis CD8 cells predominated in the upper synovial region and CD4 cells in the cellular aggregates. Plasma cells were rarely found in osteoarthritic synovia, but were common in rheumatoid arthritis, with IgG-producing plasma cells predominating. Morphometric studies of representative synovial samples may help to improve histological diagnosis and our understanding of pathological mechanisms.

Aged↗
PubMed1987

The movement of muscle precursor cells between adjacent regenerating muscles in the mouse.

Regeneration of mature skeletal muscle fibres involves the formation of new multinucleate muscle fibres by the fusion together of mononucleate muscle precursor cells. Such precursor cells appear to be largely or entirely derived from satellite cells, located between the basement membrane and the sarcolemma of the muscle fibre. We have previously presented evidence that precursor cells which contribute to regenerating muscle in a region of muscle damage are not all locally derived but that some migrate in from exogenous sources. The present study examines the possibility that a regenerating muscle might receive muscle precursor cells from neighbouring muscles. To do this we have made whole muscle allografts in the mouse and used the two murine isoenzyme allotypes of the dimeric enzyme Glucose-6-Phosphate Isomerase (GPI) as markers to demonstrate whether there is movement of muscle precursor cells between these allografts and adjacent host muscles. In host muscles adjacent to some allografts, a "hybrid" form of GPI was detected, each molecule consisting of one donor and one host GPI subunit. Such heterodimers can form only where host and donor nuclei share a common cytoplasm: in muscles this means that mosaic host/donor muscle fibres are present. The presence of such fibres implies that muscle precursor cells must have migrated into the host muscle from the neighbouring allograft.

Animals↗
PubMed1987

Muscle precursor cells invade and repopulate freeze-killed muscles.

A problem with the use of muscle grafting as a therapeutic procedure is to produce a graft functionally adequate to replace a muscle of complex architecture, such as a sphincter muscle. We thought it might be possible to use dead cadaver muscles, repopulated by the patient's own muscle precursor cells (mpc), to reconstruct muscles whose anatomy would be imposed by the framework of dead muscle and whose genetic constitution would be determined by the mpc. Here we show, in the mouse, that an extensor digitorum longus (EDL) muscle, killed by repeated freezing and thawing, repopulated with mpc and grafted into a nu/nu or tolerant AKR host mouse, is capable of supporting muscle formation. By using the allotypic isoenzyme forms of glucose-6-phosphate isomerase as markers, we have shown that the newly regenerated muscle in such grafts is derived mainly from the implanted mpc, but also to some extent from the host mouse's own mpc. By 50-70 days after grafting, new muscle fibres were found to constitute up to 70% of the graft. Many fibres had assumed diameters in the normal range for mouse muscle, often having peripherally placed nuclei. These findings raise the possibility of the therapeutic use of such grafts. To our surprise, dead EDL muscle grafts into which no mpc had been implanted were also the site of good muscle regeneration. New-formed muscle in these grafts was shown to be derived entirely from mpc which must have migrated into the graft from the host. Investigation of the mechanisms underlying this phenomenon should further our knowledge of factors which regulate the proliferation and movement of dormant mpc in adult animals.

Animals↗
PubMed1984

Long term survival of allografted muscle precursor cells following a limited period of treatment with cyclosporin A.

Previous work (Watt et al., 1982) has shown that, in the mouse, skeletal muscle can be transplanted successfully in the form of a suspension of it's mononucleate precursors. Eventual therapeutic application of this technique by the implantation of precursor cells derived from normal muscle into myopathic individuals would require a means of preventing allograft rejection applicable to man. We have therefore investigated the use of the drug cyclosporin A (CyA) as a means of prolonging the survival in mice of allografts of mononucleate muscle cells made into a region of regenerating host muscle. We have administered CyA to the hosts at doses of either 75 or 150 mg/kg body weight/day for 42 days from the day of grafting. By using isoenzyme allotypes as markers of host and donor tissues, we have shown that allografted mononucleate cells become incorporated in host muscle fibres and that the mosaic host/donor muscle fibres so formed survive for as long as we continued the experiment, a maximum of 107 days after grafting, or 65 days after the end of CyA treatment.

Animals↗
PubMed1983

Isoenzyme studies of whole muscle grafts and movement of muscle precursor cells.

Isoenzymes of glucose-6-phosphate isomerase (GPI: E.C. 5.3.1.9) were used as markers to determine the origin of cells which give rise to new muscle formed in allografts of whole intact muscle. GPI isoenzymes were also employed to see whether host precursor cells, which have been shown to contribute to muscle formation in grafts of minced muscle, can be derived from muscle lying adjacent to grafts. Excellent muscle regeneration was found in allografts of extensor digitorum longus (EDL) muscle examined after 58 days: 12 of 16 grafts contained 80% or more new muscle. Isoenzyme analysis showed that most, and in 2 instances all, new muscle was derived from implanted donor cells; however, there was strong evidence that in 5 grafts some, or all, new muscle must have resulted from host cells moving into the graft. Although hybrid isoenzyme was not detected this was attributed to factors associated with host tolerance which appear to interfere with fusion between host and donor myoblasts. Isografts of minced muscle were placed next to whole EDL muscle allografts to see if cells from allografts moved into adjacent regenerating tissue. Unfortunately, muscle regeneration in minced isografts was poor; only 3 contained 50% or more new muscle and most contained large amounts of fibrous connective tissue. Only a single isoenzyme band was detected in 11 isografts, but in five instances, the presence of a second band showed that cells from EDL allografts were also present. As no hybrid isoenzyme was detected, it is not known whether these cells which had moved into the regenerating minced grafts were muscle precursors, fibroblasts or some other cell types.

Animals↗
PubMed1982

Incorporation of donor muscle precursor cells into an area of muscle regeneration in the host mouse.

Normal muscle precursor cells, prepared by the enzymatic disaggregation of neonatal mouse muscle, were implanted into an area of regenerating muscle in a genetically different inbred strain. This was done in an attempt to determine, first, whether donor muscle precursor cells prepared in this way would fuse with the developing muscle fibres of the host; and second, whether in the "mosaic" muscle fibres thus formed donor as well as host genes were expressed. As markers of the host and donor genes we used the allelic isoenzyme variants of glucose-6-phosphate isomerase (GPI). In 43 out of 60 grafts we detected the presence of a "hybrid" isoenzyme intermediate between host and donor types. This "hybrid" indicated that donor muscle precursor cells had fused with regenerating host muscle cells, and had expressed their GPI genes within the resulting mosaic muscle fibres. We have developed this technique with a view to inserting normal genes into genetically abnormal myopathic muscle.

Animals↗
PubMed1981

Cyclosporin A as a means of preventing rejection of skeletal muscle allografts in mice.

Isografts and allografts of skeletal muscle inserted into the limbs of mice initially degenerate. After some 5 to 8 days newly formed myotubes appear in the graft which develop into mature muscle fibers. In nontolerant hosts allografts are rejected between the 10th and 12th days. In mice treated with cyclosporin A, this effect persists for some 12 days after the end of treatment. Isoenzyme marker studies indicate that the regenerated graft is composed of both host and donor tissue. Donor isoenzyme does not persist when grafts are rejected.

Animals↗
PubMed1980

The contribution of exogenous cells to regenerating skeletal muscle: an isoenzyme study of muscle allografts in mice.

A sequential study of 180 allografts of minced skeletal muscle has been made in mice, in 124 of which tolerance was induced. The host/donor composition of grafts was assessed in terms of their content of isoenzymes of glucose-6-phosphate isomerase characteristic of host and donor strains. From 0-5 days implanted muscle fibre fragments uniformly underwent degeneration. New myotubes appeared at day 5. Both host and donor isoenzyme were found during this period. In "non-tolerant" hosts, grafts were rejected at 8-12 days, after which only host isoenzyme was found and the graft site usually lacked muscle, consisting of fibrofatty connective tissue. In the few instances where muscle was found in such grafts, this was necessarily formed from host precursor cells which had migrated into the graft site. In "tolerant" hosts, grafts contained up to 80 per cent. of the muscle and usually yielded both host and donor isoenzyme. Where "hybrid" isoenzyme was found, it was probable that host muscle precursor-cells had entered grafts and fused with donor muscle.

Animals↗