Irintchev A, Zweyer M, Wernig A
Department of Physiology, University of Bonn, Germany.
J Neurocytol. 1995 Apr;24(4):319-31. doi: 10.1007/BF01186543.
Implantation of skeletal muscle precursor cells is a potential means of cell-mediated gene therapy. One unresolved question is the degree of immunogenicity of such myoblasts. We designed the extreme situation of implanting cells of a non-histocompatible myoblast cell line into cryodamaged, but regeneration-capable, muscles of adult mice. Without immunosuppression donor cells are rejected within the first weeks. Immunosuppression with Cyclosporin A prevented invasion of T-lymphocytes and allowed differentiation of implanted myoblasts into myofibres as well as down-regulation of MHC expression. Still, withdrawal of Cyclosporin A after 4 weeks triggered lymphocyte invasion and cytotoxic cell reactions with rejection of donor tissue. Although the vast majority of muscle fibres was MHC-negative 1-4 days after Cyclosporin A withdrawal, single small desmin-positive profiles were weakly positive for donor MHC. Parallel with the increase in the number of lymphocytes, larger numbers of small and large muscle fibres expressed high levels of either donor, host or both, class I--but not class II--molecules. Surprisingly, immune reactions continued over several months, causing gradual loss of muscle tissue. Donor class I molecules persisted for more than 6 months after Cyclosporin A withdrawal, clearly indicating survival of donor muscle fibres despite ongoing rejection. Indirect evidence on the other hand suggests additional loss of host fibres, possibly caused by cytokine release from the immune cells (bystander damage). We conclude that transient treatment with Cyclosporin A induced a kind of tolerance related to the maturation and down-regulation of class I antigens in donor muscle fibres. It is suggested that the start of immune reaction following Cyclosporin A withdrawal is initiated by remaining small amounts of donor MHC molecules, possibly related to the continuous proliferation of the cell-lined-derived donor myoblasts.
植入骨骼肌前体细胞是细胞介导基因治疗的一种潜在手段。一个尚未解决的问题是此类成肌细胞的免疫原性程度。我们设计了一种极端情况，即将非组织相容性成肌细胞系的细胞植入成年小鼠经冷冻损伤但仍具备再生能力的肌肉中。在没有免疫抑制的情况下，供体细胞在最初几周内就会被排斥。用环孢素A进行免疫抑制可防止T淋巴细胞的侵入，并使植入的成肌细胞分化为肌纤维，同时下调MHC的表达。然而，4周后停用环孢素A会引发淋巴细胞侵入和细胞毒性细胞反应，导致供体组织被排斥。尽管在停用环孢素A后1 - 4天，绝大多数肌纤维的MHC呈阴性，但单个小的结蛋白阳性细胞轮廓对供体MHC呈弱阳性。随着淋巴细胞数量的增加，越来越多的小肌纤维和大肌纤维表达高水平的供体、宿主或两者的I类分子（而非II类分子）。令人惊讶的是，免疫反应持续了数月，导致肌肉组织逐渐丧失。停用环孢素A后，供体I类分子持续存在超过6个月，这清楚地表明尽管存在持续的排斥反应，供体肌纤维仍存活。另一方面，间接证据表明宿主纤维可能因免疫细胞释放的细胞因子（旁观者损伤）而进一步丧失。我们得出结论，用环孢素A进行短暂治疗可诱导一种与供体肌纤维中I类抗原的成熟和下调相关的耐受性。有人认为，停用环孢素A后免疫反应的启动是由残留的少量供体MHC分子引发的，这可能与细胞系衍生的供体成肌细胞的持续增殖有关。
