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Biomedical subjects

M K Brenner

Publications and source records attributed to M K Brenner.

At least 91 records · Page 5Linked to original sources
PubMed1996

Gamma delta T lymphocyte regeneration after T lymphocyte-depleted bone marrow transplantation from mismatched family members or matched unrelated donors.

The recovery of gamma delta T lymphocytes was studied in 31 recipients of T cell-depleted allogeneic bone marrow (BMT) to determine if the dynamics of reconstitution could be related to graft-versus-host disease (GVHD) or other complications of marrow transplantation. Two distinct patterns of regeneration were apparent. In 12 patients, there was a progressive rise in both the percentage and the absolute number of peripheral blood gamma delta T cells over the first year post-transplantation, but these increases never breached levels found in 14 healthy donors. Each of the 19 remaining patients had abnormally high proportions and numbers of gamma delta T cells on at least two occasions following transplantation. The clinical factor that best explained these observations was the frequency of intercurrent infections. Of 19 patients with abnormally increased percentages and numbers of gamma delta T lymphocytes, 18 had one or more episodes of confirmed viral or fungal infection, contrasted with only two of 12 in the comparison group (P < 0.001). There was no significant association of gamma delta T cell recovery patterns with the presence of GVHD (P = 0.33). We conclude that the recovery of gamma delta T lymphocytes after marrow transplantation may vary. Supranormal levels of this T cell subset are associated with infection and may contribute significantly to cellular immune defenses against fungal or viral disease.

Adolescent↗
PubMed1996

Use of gene marking in bone marrow transplantation.

We have used gene marking to investigate the mechanism of relapse and biology of reconstitution following bone marrow transplantation (BMT). The rationale for our initial protocols was to learn if residual malignant cells in autologous marrow contribute to subsequent relapse. Marked malignant cells were found at the time of relapse in 6/8 patients relapsing after autologous BMT for AML or neuroblastoma showing the infused marrow contributed to disease recurrence. Modifications of this marker approach with two distinguishable vectors are now being used to compare the efficacy of purging techniques. We were also able to evaluate gene transfer to normal progenitors and demonstrated that the marker gene was expressed for up to 36 months. Gene marking is also being used to trace the fate of EBV-specific CTLs that we are administering to recipients of allogeneic BMT and has provided evidence of persistence of adoptively transferred CTL for up to 10 months.

Bone Marrow Purging↗
PubMed1996

Gene marking.

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Genetic Markers↗
PubMed1996

Transfer of marker genes into hemopoietic progenitor cells.

Ex vivo gene marking of normal and malignant hemopoietic cells allows the cells to be subsequently tracked in vivo. Marking has shown that even when marrow is in remission, it may contain malignant cells that contribute to relapse. These studies have also shown that it is possible to obtain long-term gene expression in human long-lived hemopoietic progenitor cells and T lymphocytes in vivo. Current marker studies use two distinguishable vectors to track two distinctively treated cell populations in a single individual. This modification greatly increases the power of the technique. It is now possible to study the effects of purging on residual malignant cells in marrow, to determine the action of growth-promoting agents (such as cytokines and stroma) on short- and long-term repopulation by transduced marrow, and to discover which phenotypic subsets of hemopoietic progenitor cells have long-term repopulating potential. The information gained will be invaluable for improving therapeutic gene transfer protocols in which marrow-derived cells are the targets.

Bone Marrow Cells↗
PubMed1995

Response of steroid-resistant graft-versus-host disease to lymphoblast antibody CBL1.

Therapy of steroid-resistant graft-versus-host disease (GVHD) with antibodies to T cells or cytokines is of limited value because GVHD is mediated by a pleomorphic group of effective cells and cytokines. CBL-1, a murine monoclonal antibody, recognises an antigen on activated T cells, B cells, and natural killer cells. We administered CBL-1 to ten patients with grade III or IV steroid-resistant GVHD. Complete remissions occurred in five cases and partial remissions in four. The organ system(s) affected by GVHD was not a predictor of response. CBL-1 was well tolerated and did not exacerbate post-transplant immunodeficiency. Our findings support the use of CBL-1 in primary prophylaxis for GVHD.

Adolescent↗
PubMed1995

Use of gene-modified virus-specific T lymphocytes to control Epstein-Barr-virus-related lymphoproliferation.

Reactivation of Epstein-Barr virus (EBV) after bone-marrow transplantation leads in many cases to lymphoproliferative disease that responds poorly to standard therapy and is usually fatal. To prevent or control this complication, we prepared EBV-specific cytotoxic T-lymphocyte (CTL) lines from donor leucocytes and infused them into ten allograft recipients. Three of the patients had shown signs of EBV reactivation, with or without overt lymphoproliferation, and the others received CTL infusions as prophylaxis. No patient developed any complication that could be attributed to the CTL infusions. In the three patients with EBV reactivation, EBV DNA concentrations (measured by semiquantitative polymerase chain reaction [PCR]), which had increased 1000-fold or more, returned to the control range within 3-4 weeks of immunotherapy. The most striking consequence was the resolution of immunoblastic lymphoma in a 17-year-old patient who received four CTL infusions (two 1 x 10(7)/m2 and two 5 x 10(7)/m2). Because the CTL had been genetically marked before infusion, we were able to show by PCR analysis that they persisted for 10 weeks after administration. EBV-specific donor-type T-cell lines seem to offer safe and effective therapy for control of EBV-associated lymphoproliferation.

Adolescent↗
PubMed1995

The contribution of marker gene studies to hemopoietic stem cell therapies.

Although the transfer of "therapeutic" genes into hemopoietic stem cells (HSC) offers many opportunities to treat a wide range of human disease, the low efficiency of transfer and limited expression of the transferred gene have so far largely prevented any direct beneficial effect from being obtained. However, gene marker studies in which the transferred genes are used simply to track the individual components of the infused HSC have already shown their utility. Genetic marking may be used to identify cells capable of causing relapse after autologous bone marrow transplantation and to distinguish cells in the graft capable of preventing malignant disease. Marking may also be used to analyze the consequences of ex vivo or in vivo manipulations of the HSC which are intended to accelerate engraftment or augment gene transfer efficiencies. Information obtained from these studies should therefore not only improve the outcome of HSC based therapies, but also aid in the introduction of successful gene therapy protocols.

Bone Marrow Transplantation↗
PubMed1995

Gene-marking and haemopoietic stem-cell transplantation.

Gene transfer has allowed a number of biological issues in haematopoietic stem-cell transplantation to be addressed. Gene-marking studies have shown that residual malignant cells in infused marrow may contribute to relapse in acute myeloid leukaemia, neuroblastoma and chronic myeloid leukaemia. Double gene-marking techniques with distinguishable retroviral vectors are being used to compare purging techniques and the reconstitution of different sources of stem cells. In allogeneic bone-marrow transplantation, gene-marking has demonstrated that adoptively transferred cytotoxic T cells can persist and reconstitute antiviral immunity.

Adoptive Transfer↗
PubMed1995

Production of genetically modified Epstein-Barr virus-specific cytotoxic T cells for adoptive transfer to patients at high risk of EBV-associated lymphoproliferative disease.

EBV-induced lymphoproliferative disease (EBV-LPD) is a disorder most commonly associated with the immunocompromise that follows allogeneic organ transplantation. In patients receiving T cell-depleted bone marrow from HLA-mismatched or HLA-matched unrelated donors, the incidence of EBV-LPD is particularly high, ranging from 5 to 30%. Administration of EBV-specific cytotoxic T lymphocytes may be one means of preventing and treating this disease. We now describe a method that allows the routine and timely preparation of large numbers of such cells to allow their safe administration to bone marrow transplant recipients. We also describe how these cells may be genetically marked before infusion, to determine their fate and disposition in vivo.

Adolescent↗
PubMed1995

Gene transfer into human hemopoietic progenitor cells.

Considerable progress is being made in the transfer of genetic material to hematopoietic stem cells. In this chapter we describe how gene transfer is being used to: mark marrow and peripheral blood progenitor cells prior to autologous transplantation, to track their fate on reinfusion and to detect contaminating tumorigenic cells; modulate immunocyte function--important in immunologic disorders and perhaps in cancer therapy; generate tumor vaccines from tumor cells isolated from marrow; correct single gene defects--the 'classical' concept of gene therapy; and finally to modify the drug sensitivity of progenitor cells--enabling them to resist the suppressive effects of cytotoxic drugs during cancer therapy and perhaps providing a mechanism for in vivo selection of gene modified cells.

Animals↗
PubMed1995

Early identification of Epstein-Barr virus-associated post-transplantation lymphoproliferative disease.

Epstein-Barr virus-associated lymphoproliferative disease (EBV-LPD) is a common, usually fatal, complication developing after transplantation of bone marrow from HLA-mismatched or HLA-matched unrelated donors. Prompted by recent reports of successful treatment of EBV-LPD, we investigated methods which could result in early identification of patients at high risk for this disorder, thus improving the likelihood of successful therapeutic interventions. Both the outgrowth of transformed B lymphocytes ex vivo (100% correlation) and the detection of EBV DNA by a PCR method (80% correlation) showed statistically significant association with the histopathological diagnosis of EBV-LPD. Because these abnormalities can be detected prior to the onset of clinical disease. It should now be possible to use a combination of the methods described here to identify patients at high risk of developing EBV-LPD, thus enabling early therapeutic intervention.

Adolescent↗
PubMed1995

Human somatic gene therapy: progress and problems.

Whilst the potential of gene therapy is considerable, current applications have been restricted by the limitations of available vectors. As yet, no vector is able to produce the desired safe, targeted and efficient transfer of genetic material with regulation of the new gene in the targeted cell. Notwithstanding these limitations, more than 65 clinical gene transfer protocols have been approved in the US. The majority of these are open to patients with malignant disease, in whom the risk:benefit ratio is most appropriate. Current progress and problems in gene transfer are illustrated by reference to gene transfer into haemopoietic stem cells (HSC), an area that has attracted particular attention, both because of the logistic advantages of these cells and because of the wide range of pathologies that may be corrected in the HSC itself or in its progeny. Because of the low efficiency of transfer into HSC, initial studies have involved transfer of marker genes to determine the origin of relapse after autologous bone marrow transplantation and to learn more about the conditions that enhance gene transfer and expression in haemopoietic tissue. Information gained from these studies is already guiding the practice of autologous and allogeneic marrow transplantation and has contributed to the development of gene therapy protocols for the treatment of malignant disease, immune deficiency syndromes and lysosomal storage disorders. Over the next decade, as the technology of gene transfer advances, many further clinical applications of the approach will become evident.

Genetic Therapy↗
PubMed1995

The use of cytokines to improve gene transfer to human hematopoietic stem cells.

The introduction of a new gene into the DNA of a hematopoietic stem cell (HSC) offers the potential for permanent repopulation of a host with functionally modified stem cells and their progeny. At present, retroviral vectors are the only integrating agents available for clinical use. Because these vectors function only in dividing cells, cycling of the target cell is a current requirement for permanent gene transfer. Few HSC are in cycle, so until clinical-grade vectors are developed that integrate in resting cells, stimulation with cytokine combinations will likely be an important component of successful gene therapy protocols. The relationship between cytokines and gene transfer may be of benefit in another way. Marker genes can be used to analyze the effects of cytokines on HSC growth and differentiation. Since two or more distinctive markers can be added to separately treated portions of the HSC, it is possible to compare simultaneously in a single individual the effects of multiple ex vivo cytokine treatments on subsequent HSC engraftment. This approach should greatly simplify the development of optimal ex vivo expansion regimens for accelerated and permanent engraftment in patients receiving infusions of HSC.

Animals↗
PubMed1994

Direct demonstration that autologous bone marrow transplantation for solid tumors can return a multiplicity of tumorigenic cells.

Patients with solid tumors are increasingly being treated by autologous bone marrow transplantation (BMT). Although response rates appear to be increased, disease recurrence is the commonest cause of treatment failure. Whether relapse is entirely due to residual disease in the patient or arises also from infiltrating malignant cells contained in the autologous marrow transplant has not been resolved. If the latter explanation is correct, then purging would be required as part of the transplantation procedure. We used retrovirally mediated transfer of the neomycin-resistance gene to mark BM harvested from eight patients with neuroblastoma in clinical remission. The marked marrow cells were subsequently reinfused as part of an autologous BMT. At relapse, we sought the marker gene in malignant cell populations. Three patients have relapsed, and in each the marker gene was detected by phenotypic and genetic analyses of resurgent malignant cells at medullary and extramedullary sites. Analysis of neuroblast DNA for discrete marker gene integration sites suggested that at least 200 malignant cells, each capable of tumor formation, were introduced with the autologous marrow transplant and contributed to relapse. Thus, autologous BMTs administered to patients with this solid tumor may contain a multiplicity of malignant cells that subsequently contribute to relapse. The marker-gene technique we describe should permit evaluation of the mechanisms of relapse and the efficacy of purging in patients receiving autologous marrow transplantation for other solid tumors that infiltrate the marrow.

Base Sequence↗
PubMed1994

Gene marking and autologous bone marrow transplantation.

If residual cancer cells in harvested bone marrow could be marked and subsequently detected in patients at relapse, valuable information would be obtained about the source of recurrent disease after autologous marrow transplantation. If normal progenitor cells were also marked, the study would provide useful data on the susceptibility of these human cells to gene transfer and their capacity to express newly introduced genes. We transferred the neomycin-resistance gene (NeoR) into bone marrow cells harvested from 20 children with acute myeloid leukemia (n = 12) or neuroblastoma (n = 8) in clinical and cytological remission using a retrovirus vector. The cells were then returned to the patients as part of an autologous bone marrow transplantation protocol. Two AML and three neuroblastoma patients have relapsed. In all, the resurgent cells contained the NeoR marker by analysis with PCR. These results prove that so-called remission marrow can contribute to relapse in patients who receive autologous transplants. The gene marking technique is now being used to evaluate techniques of pretransplant purging.

Bone Marrow Transplantation↗
PubMed1994

Genetic marking and manipulation of hematopoietic progenitor cells using retroviral vectors.

In the 5 years since the first human gene therapy studies began, more than 70 clinical protocols have been approved, and over 200 patients have received genetically modified cells. A high proportion of these protocols have made use of hematopoietic progenitor cells or their mature progeny. In this review, we discuss the progress and limitations of current clinical gene transfer studies using marrow-derived progenitor cells and describe how the technique is being applied to the treatment of single-gene disorders and to augment cancer immunotherapies. We also discuss the contribution made by gene marking studies.

Cell Separation↗