Adeno-associated virus-mediated vascular endothelial growth factor gene therapy in skeletal muscle before transplantation promotes revascularization of regenerating muscle

Successful clinical transplantation of whole skeletal muscles can be limited by impaired muscle revascularization and regeneration. The aim of this study was to enhance the revascularization (and hence speed of regeneration) of transplanted whole muscles by transducing muscles with the vascular endothelial growth factor (VEGF) gene before transplantation, using a recombinant adeno-associated virus (rAAV). The rAAV encoding VEGF and green fluorescent protein (GFP) (rAAV.VEGF.GFP) was injected into the tibialis anterior muscles of adult BALB/c mice. One month after injection whole muscle autotransplantation was performed. Muscles were sampled 7 days after autografting. GFP expression was examined as an indicator of persistent transgene expression after grafting, and immunohistochemistry was used to identify VEGF, blood vessels, and newly formed myotubes. After grafting, GFP expression persisted only in a few surviving myofibers in the periphery of rAAV.VEGF.GFP-pretreated muscles, although abundant VEGF expression was seen in myogenic cells in all grafted muscles. Quantitative analysis demonstrated that, although only small numbers of rAAV.VEGF.GFP-transduced myofibers were present, whole muscle grafts preinjected with rAAV.VEGF.GFP were significantly more vascular than saline-injected and uninjected control muscle grafts. Furthermore, rAAV.VEGF.GFP-injected whole muscle transplants were further advanced in terms of regeneration (myotube formation) compared with the uninjected control muscle transplants. This study clearly shows that rAAV-mediated VEGF expression persists only in myofibers that survive the necrosis induced by muscle transplantation; however, this amount of VEGF results in significantly increased revascularization and regeneration of whole muscle transplants.     

Protein thiol oxidation does not change in skeletal muscles of aging female mice

Oxidative stress caused by reactive oxygen species is proposed to cause age related muscle wasting (sarcopenia). Reversible oxidation of protein thiols by reactive oxygen species can affect protein function, so we evaluated whether muscle wasting in normal aging was associated with a pervasive increase in reversible oxidation of protein thiols or with an increase in irreversible oxidative damage to macromolecules. In gastrocnemius muscles of C57BL/6J female mice aged 3, 15, 24, 27, and 29 months there was no age related increase in protein thiol oxidation. In contrast, there was a significant correlation (R ² = 0.698) between increasing protein carbonylation, a measure of irreversible oxidative damage to proteins, and loss of mass of gastrocnemius muscles in aging female mice. In addition, there was an age-related increase in lipofuscin content, an aggregate of oxidised proteins and lipids, in quadriceps limb muscles in aging female mice. However, there was no evidence of an age-related increase in malondialdehyde or F₂-isoprostanes levels, which are measures of oxidative damage to lipids, in gastrocnemius muscles. In summary, this study does not support the hypothesis that a pervasive increase in protein thiol oxidation is a contributing factor to sarcopenia. Instead, the data are consistent with an aging theory which proposes that molecular damage to macromolecules leads to the structural and functional disorders associated with aging.     

Randomized controlled trial to investigate influence of the fluid challenge on duration of hospital stay and perioperative morbidity in patients with hip fractures

Background. A prospective, randomized controlled trial comparingconventional intraoperative fluid management with two differingmethods of invasive haemodynamic monitoring to optimize intraoperativefluid therapy, in patients undergoing proximal femoral fracturerepair under general anaesthesia. Methods. Ninety patients randomized to three groups; conventionalintraoperative fluid management (Gp CON, n=29), and two groupsreceiving additional repeated colloid fluid challenges guidedby central venous pressure (Gp CVP, n=31) or oesophageal Dopplerultrasonography (Gp DOP, n=30). Primary outcome measures weretime to medical fitness to discharge, hospital stay and postoperativemorbidity. Results. The fluid challenge resulted in significantly greaterperioperative changes in central venous pressure between GpCVP and Gp CON (mean 5 (95% confidence interval 3–7) mmHg) (P<0.0001). Important perioperative changes were alsoshown in Gp DOP with increases of 49.4 ms (19.7–79.1 ms)in the corrected flow time, 13.5 ml (7.4–19.6 ml) in strokevolume, and 0.9 (0.49–1.39) litre min^–1 in cardiacoutput. As a result, fewer patients in Gp CVP and Gp DOP experiencedsevere intraoperative hypotension (Gp CON 28% (8/29), Gp CVP9% (3/31), Gp DOP 7% (2/30), P=0.048 (chi-squared, 2 degreesof freedom (df)). No differences were seen between the threegroups when major morbidity and mortality were combined, P=0.24(chi-squared, 2 df). Postoperative recovery for survivors, asdefined by time to be deemed medically fit for discharge, wassignificantly faster, in comparison with Gp CON, in both theGp CVP (10 vs 14 (95% confidence interval 8–12 vs 12–17)days, P=0.008 (t-test)), and Gp DOP (8 vs 14 (95% confidenceinterval 6–12 vs 12–17) days, P=0.023 (t-test).There were no significant differences between groups, for survivors,with respect to acute orthopaedic hospital and total hospitalstay. Conclusions. Invasive intraoperative haemodynamic monitoringwith fluid challenges during repair of femoral fracture undergeneral anaesthetic shortens time to being medically fit fordischarge. Br J Anaesth 2002; 88: 65–71     

Why do cultured transplanted myoblasts die in vivo? DNA quantification shows enhanced survival of donor male myoblasts in host mice depleted of CD4+ and CD8+ cells or Nk1.1+ cells

Overcoming the massive and rapid death of injected donor myoblasts is the primary hurdle for successful myoblast transfer therapy (MTT), designed as a treatment for the lethal childhood myopathy Duchenne muscular dystrophy. The injection of male myoblasts into female host mice and quantification of surviving male DNA using the Y-chromosome-specific (Y1) probe allows the speed and extent of death of donor myoblasts to be determined. Cultured normal C57BL/10Sn male donor myoblasts were injected into untreated normal C57BL/10Sn and dystrophic mdx female host mice and analyzed by slot blots using a 32P-labeled Y1 probe. The amount of male DNA from donor myoblasts showed a remarkable decrease within minutes and by 1 h represented only about 10-18% of the 2.5 x 10(5) cells originally injected (designated 100%). This declined further over 1 week to approximately 1-4%. The host environment (normal or dystrophic) as well as the extent of passaging in tissue culture (early "P3" or late "P15-20" passage) made no difference to this result. Modulation of the host response by CD4+/CD8+ -depleting antibodies administered prior to injection of the cultured myoblasts dramatically enhanced donor myoblast survival in dystrophic mdx hosts (15-fold relative to untreated hosts after 1 week). NK1.1 depletion also dramatically enhanced donor myoblast survival in dystrophic mdx hosts (21-fold after 1 week) compared to untreated hosts. These results provide a strategic approach to enhance donor myoblast survival in clinical trials of MTT.     

Strength at the extracellular matrix-muscle interface

Mechanical force is generated within skeletal muscle cells by contraction of specialized myofibrillar proteins. This paper explores how the contractile force generated at the sarcomeres within an individual muscle fiber is transferred through the connective tissue to move the bones. The initial key point for transfer of the contractile force is the muscle cell membrane (sarcolemma) where force is transferred laterally to the basement membrane (specialized extracellular matrix rich in laminins) to be integrated within the connective tissue (rich in collagens) before transmission to the tendons. Connections between (1) key molecules outside the myofiber in the basement membrane to (2) molecules within the sarcolemma of the myofiber and (3) the internal cytoplasmic structures of the cytoskeleton and sarcomeres are evaluated. Disturbances to many components of this complex interactive system adversely affect skeletal muscle strength and integrity, and can result in severe muscle diseases. The mechanical aspects of these crucial linkages are discussed, with particular reference to defects in laminin-alpha2 and integrin-alpha7. Novel interventions to potentially increase muscle strength and reduce myofiber damage are mentioned, and these are also highly relevant to muscle diseases and aging muscle.     

Superior survival and proliferation after transplantation of myoblasts obtained from adult mice compared with neonatal mice

BACKGROUND: Myoblast transfer therapy (MTT) is a strategy designed to compensate for the defective gene in myopathies such as Duchenne muscular dystrophy (DMD). Experimental MTT in the mdx mouse (an animal model of DMD) has used donor myoblasts derived from mice of various ages; however, to date, there has been no direct quantitative comparison between the efficacy of MTT using myoblasts isolated from adult and neonate donor muscle. METHODS: Donor normal male myoblasts were injected into Tibialis Anterior muscles of dystrophic female host mice and the survival and proliferation of male myoblasts quantitated using Y-chromosome specific real-time quantitative polymerase chain reaction. The survival of late preplate (PP6) myoblasts derived from neonatal (3-5 days old) or adult (6-8 weeks old) donor mice after MTT were compared. The influence of the number of tissue culture passages, on survival post-MTT, was also evaluated for both types of myoblasts. RESULTS: Surprisingly, superior transplantation efficiency was observed for adult-derived compared with neonatal myoblasts (both early and late passage). Extended expansion (>17 passages) in tissue culture resulted in inferior survival and proliferation of both adult and neonatal myoblasts; however, proliferation of early passage myoblasts (both adult and neonate) was evident between 3 weeks and 3 months. CONCLUSIONS: Myoblasts derived from neonatal mice were inferior for transplantation, and early passage donor myoblasts from adult mice are recommended for MTT in this model.     

Forensic psychiatry and political controversy

This article gives a U.K.-based perspective on the involvement of forensic psychiatry organizations in questions of political controversy. Medical professional bodies are fundamentally concerned to uphold good standards of clinical practice and patient welfare, and to uphold professional medical ethics. In our specialty, when acting as individual expert witnesses, we seek to serve the courts with objectivity and respect for the law. However, as members of our professional bodies we have a legitimate medical concern about how the law affects the mentally disordered as a class. We should articulate a collective view about what treating the mentally disordered justly and appropriately in the legal system means and should challenge the law when it fails to achieve this.