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K Seidel

Publications and source records attributed to K Seidel.

At least 37 records · Page 2Linked to original sources
PubMed1999

Interleukin-1 inhibits gamma interferon-induced bacteriostasis in human uroepithelial cells.

The most prominent gamma interferon (IFN-gamma)-induced antimicrobial effector mechanisms are the induction of nitric oxide (NO) synthase (NOS) and of indoleamine 2,3-dioxygenase (IDO) activity. We have recently found that human glioblastoma cells and human macrophages inhibit the growth of group B streptococci after stimulation with IFN-gamma. In this report, we show that in addition, human RT4 (uroepithelial) cells can inhibit the growth of enterococci. Murine macrophages (RAW cells) are unable to inhibit bacterial growth after IFN-gamma stimulation. Stimulation of human glioblastoma cells, macrophages, and RT4 cells with human IFN-gamma results in a strong expression of IDO activity; however, NO production remains undetectable. In strong contrast, murine RAW cells produce large amounts of NO when stimulated with murine IFN-gamma and IDO activity is not detectable. Interleukin-1 (IL-1) induces NO synthase in human RT4 cells when the cells are costimulated with IFN-gamma. We found that IL-1 inhibits IFN-gamma-stimulated IDO activity and antimicrobial effects in RT4 cells, while in human glioblastoma cells, which lack detectable NO synthase activity, neither of these effects was altered by costimulation with IFN-gamma and IL-1. The IL-1-mediated inhibition of IDO activity and of subsequent antibacterial effect is due to the production of NO. This conclusion was supported by evidence that N(G)-monomethyl-L-arginine, a competitive inhibitor of inducible NOS activity, is able to block the inhibitory action of IL-1 on IFN-gamma-induced bacteriostasis. We therefore conclude that NO production does not inhibit the growth of enterococci but might be involved in the regulation of IDO activity in some human cells.

Animals↗
PubMed1999

Prevalence of hepatitis C virus antibodies and genotypes in asymptomatic, first-time blood donors in Namibia.

Reported is the prevalence of hepatitis C virus (HCV) in Namibia as determined using a third-generation enzyme-linked immunosorbent assay (ELISA) on samples of blood collected from all asymptomatic, first-time blood donors between 1 February and 31 July 1997 (n = 1941). The HCV seroprevalence was 0.9% (95% confidence interval (CI): 0.5-1.5%) and no associations were detected between a positive HCV serostatus and the person's sex, region of residence, or previous hepatitis B exposure or hepatitis B carrier status, as determined by hepatitis B surface antigen (HBsAg). The only significant association in a logistic regression model was an increase in HCV positivity with increasing age (P = 0.04). Viral RNA was amplified from 2 out of 18 (11.1%) specimens that were ELISA positive. Genotyping of these specimens, by restriction fragment length polymorphism (RFLP), showed the presence of genotypes 5 and 1a. The positive predictive value of using HBsAg positivity as a surrogate screening marker for HCV in Namibian blood donors was poor (1.6%), with low sensitivity (16.7%) and specificity (89.3%), and detecting only 3 out of 18 serologically HCV-positive specimens. The results of this first study of the prevalence and epidemiology of HCV infection in Namibia suggest that donor blood should be screened for HCV by ELISA in order to prevent the transmission of hepatitis C virus.

Adolescent↗
PubMed1998

Synergism between mycophenolate mofetil and cyclosporine in preventing graft-versus-host disease among lethally irradiated dogs given DLA-nonidentical unrelated marrow grafts.

Mycophenolate mofetil (MMF) was evaluated either alone or combined with cyclosporine (CSP) for preventing graft-versus-host disease (GVHD) in dogs given 9.2 Gy total body irradiation and DLA-nonidentical unrelated marrow grafts. Marrow autograft studies showed gut toxicity as limiting MMF side effects. Four groups were studied for GVHD prevention: six dogs in group 1 received MMF 10 mg/kg twice daily subcutaneously (SC) on days 0 to 27. They died between 8 to 28 days from infection or GVHD; survival was better than that of 72 controls given no immunosuppression (P = .04), but not different from 19 dogs given CSP. Four dogs in group 2 received MMF as described, along with CSP at 10 to 15 mg/kg twice daily on days 0 to 27. They died at 6 to 98 days from CSP-associated toxicity, weight loss, or infection. Nine dogs in group 3 received MMF SC twice daily 6 mg/kg/d for 3 days, followed by 10 mg/kg twice daily until day 27, along with CSP as described; four died between 7 to 106 days with intussusception, infection, or GVHD, and five became long-term survivors. Six dogs in group 4 received shortened MMF (21 days) and reduced doses of CSP given through day 100. Three died with GVHD or infection between days 38 to 119, and three became long-term survivors. Results support the notion of synergism between MMF and CSP, as evidenced by stable graft-host tolerance in greater than 50% of dogs.

Animals↗
PubMed1998

Dose rate-dependent sparing of the gastrointestinal tract by fractionated total body irradiation in dogs given marrow autografts.

PURPOSE: We compared gastrointestinal toxicity of single vs. fractionated total body irradiation (TBI) administered at dose rates ranging from 0.021 to 0.75 Gy/min in a canine model of marrow transplantation. METHODS AND MATERIALS: Dogs were given otherwise marrow-lethal single or fractionated TBI from dual 60Co sources at total doses ranging from 8-18 Gy and delivered at dose rates of 0.021, 0.05, 0.10, 0.20, 0.40, and 0.75 Gy/min, respectively. They were protected from marrow death by infusion of previously stored autologous marrow cells and they were given intensive supportive care posttransplant. The study endpoint was 10-day mortality from gastrointestinal toxicity. Logistic regression analyses were used to jointly evaluate the effects of dose rate, total dose, and delivery regimen on toxicity. RESULTS AND CONCLUSION: With increasing dose rates, mortality increased for either mode of delivery of TBI. With dose rates through 0.10 Gy/min, mortality among dogs given single vs. fractionated TBI appeared comparable. Beginning at 0.20 Gy/min, fractionation appeared protective for the gastrointestinal tract. Results in dogs given TBI at 0.40 and 0.75 Gy/min, respectively, were comparable, and dose fractionation permitted the administration of considerably higher total doses of TBI than were possible after single doses, an increment that was on the order of 4.00 Gy. The data indicate that the impact of fractionating the total dose at high dose rates differs from the effect of fractionation at low dose rates.

Animals↗
PubMed1998

[Idiopathic dilatation of the large intestine (Ogilvie syndrome--acute pseudo-obstruction)].

Acute colonic pseudo-obstruction (Ogilvie's syndrome) is characterized by abdominal distention and massive colonic dilatation without any mechanical cause of obstruction. We have reviewed the records of 57 patients, 36 men and 21 women (median age 65.4 y), from 1/1992 to 12/1996, with a colonic pseudo-obstruction, defined as dilatation of at least 10 cm on plain abdominal x-ray. 38 cases (66.5%) followed surgery or trauma and 19 (33.5%) developed symptoms during severe medical illness. 36 cases (63.2%) got i.v. narcotics prior to development of Ogilvie's syndrome. 4 patients underwent conservative treatment alone, 53 patients (93%) had endoscopic decompression with a decompression tube placed in 49 (86%). Due to 2 failures and 2 complications of endoscopic treatment (one ischemic lesion, one perforation; complication rate 3.8%) 4/53 patients had to be operated (7.5%). Clinical success of endoscopic treatment was 88.6% at first attempt and 92.5% at second attempt. General complications tended to be severe, according to the concomitant diseases (morbidity 35%); overall hospital mortality was 21% (12/57). In conclusion, we believe that endoscopic decompression and tube placement is effective and safe for acute colonic pseudo-obstruction not responding to 24 hour conservative treatment.

Acute Disease↗
PubMed1998

Risk of recurrence after ductal carcinoma in situ of the breast.

A cohort study was conducted to estimate the risk of breast cancer recurrence among women diagnosed with ductal carcinoma in situ (DCIS) and to identify tumor or patient characteristics that influence that risk. A population-based cancer registry was used to identify a cohort of 709 female residents of western Washington who were diagnosed with DCIS between January 1980 and June 1992 and were treated with breast-conserving surgery. Information about breast cancer recurrences, treatment, and several patient characteristics and exposures was obtained from postal questionnaires. Recurrences were confirmed using information from the cancer registry or hospital pathology reports. Approximately 15% of women experienced a recurrence within the first 5 years after diagnosis [95% confidence interval (CI), 12-18%]; 31% had a recurrence within 10 years (95% CI, 24-38%). There was a suggestion that risk was slightly elevated for women with larger tumors (> or =1.5 cm) and tumors of comedo subtype. Relative risks (RRs) were elevated for women who were premenopausal at diagnosis of DCIS (RR = 2.3; 95% CI, 1.1-5.0). Women in the upper decile of body mass index were at twice the risk of a recurrence as those women in the lower four deciles (RR = 2.3; 95% CI, 1.1-4.8). There was also a suggestion that women who used menopausal hormones for at least 2 years after their diagnosis of DCIS were at increased risk of recurrence compared to nonusers of menopausal hormones (RR = 1.8; 95% CI, 0.7-5.0). Our results suggest that the risk of recurrence may be related to some tumor characteristics as well as the hormonal milieu of the patient at or after her diagnosis of DCIS. However, larger studies are needed to more clearly document predictors of disease recurrence after DCIS.

Adult↗
PubMed1997

In vivo radioprotective effect of AcSDKP on canine myelopoiesis.

The tetrapeptide acetyl-N-Ser-Asp-Lys-Pro (AcSDKP) interferes with G1/S-phase progression, and the resulting cell cycle arrest is thought to protect hematopoietic stem cells against injury by cycle-active cytotoxic agents. We investigated the radioprotective effect of AcSDKP in a canine radiation model. Dogs were given total-body irradiation (TBI) at an exposure rate of 10 cGy/min, either without further therapy (control) or with administration of AcSDKP at 0.05-500 micrograms/ kg/24 h beginning before and continuing until after completion of TBI. At 400 cGy of TBI, one of 28 control dogs and one of eight AcSDKP-treated dogs recovered hematopoiesis (p = 0.40). At 300 cGy, seven of 21 control dogs recovered hematopoiesis compared with five of five AcSDKP-treated dogs (p = 0.01). In dogs given 300 cGy and AcSDKP, the granulocyte nadirs were less profound (p = 0.04) and occurred later (p = 0.04) than among controls; platelet kinetics did not differ. These data suggest, therefore, that AcSDKP provides a radioprotective effect in dogs exposed to 300 cGy TBI. Such an effect might be beneficial in recipients of intensive radiation therapy. Conceivably, the effect on hematopoietic recovery could be amplified by growth factor administration after irradiation.

Animals↗
PubMed1997

Glucocorticoids fail to enhance the effect of FK506 and methotrexate in prevention of graft-versus-host disease after DLA-nonidentical, unrelated marrow transplantation.

Several steroid receptor-associated heat shock proteins can bind to FK506 as immunophilins. This has led to speculation that the steroid receptor and immunophilin signal transduction pathways are functionally interrelated. Indeed, in vitro work showed that FK506 treatment of intact L929 cells which were stably transfected with various reporter plasmids resulted in a potentiation of glucocorticoid hormone-induced glucocorticoid receptor-mediated gene transcription. These findings have raised the possibility of additive or synergistic immunosuppressive effects of FK506 and glucocorticoids. We tested this hypothesis in a canine model of GVHD prevention. Two groups of dogs were given 9.2 Gy total body irradiation followed by hematopoietic grafts from unrelated DLA-nonidentical donors. Among the first group of four recipients which were given FK506 and glucocorticoids, one rejected the graft, while three developed acute GVHD and died from associated complications between days 14 and 34. In the second group of nine recipients which were given FK506, glucocorticoids and methotrexate (MTX), only one dog became a long-term survivor while eight dogs died between days 21-114 with GVHD (n = 5) or FK506-associated toxicities (n = 3). Thus, addition of glucocorticoids to FK506 or FK506/MTX showed neither synergistic nor additive effects with respect to GVHD prevention in this model, and no survival advantages were seen compared to previously reported results with FK506 alone or FK506 and MTX in combination, respectively.

Animals↗
PubMed1997

Safeguarding the administration of high-dose chemotherapy: a national practice survey by the American Society for Blood and Marrow Transplantation.

Overdoses of high-dose chemotherapy before hematopoietic cell transplantation are serious adverse events, but their frequency and etiology are unknown. The American Society for Blood and Marrow Transplantation (ASBMT) conducted an anonymous national survey to identify errors in safety practices during the administration of high-dose chemotherapy. The questionnaire was returned from 115 (68%) of 170 hematopoietic transplant centers in the United States. Ninety-four of the programs were university or affiliated centers, 19 were community hospitals, and 41 were founded since 1990. A total of 7650 transplants were reported for 1994: 22% of the programs performed 1-20 transplants, 60% performed 21-100 transplants, and 18% performed more than 100 transplants. Fifteen of the 115 responding centers reported a total of 18 patients inadvertently given overdoses of cisplatin (n=3), carboplatin (n=2), busulfan (n=2), cytosine arabinoside (n=2), cyclophosphamide (n=2), interleukin-2 (n=2), or other agents (n=5) between 1989 and 1994. Cumulative drug doses given as a daily dose (six cases) and nursing infusion errors (six cases) were the most common errors. The estimated chemotherapy overdose error rate was 0.06%, or 6 cases/10,000 transplants, with 95% confidence limits of 0.03-0.11%. The overdose rate among more experienced centers in operation before 1990 was lower than that among newer centers (p < 0.01). Large centers (> 100 transplants performed in 1994) experienced errors at rates lower than those in medium-sized centers (21-100 transplants, p = 0.03). Although the number of events was small in this self-reporting survey, overdoses were noted in 13% of the responding centers, especially among more recently established units. Safety practices need to emphasize multidisciplinary checkpoints at the physician, pharmacist, nursing, and institutional levels. Based on these survey results, ASBMT recommendations for further safeguards for high-dose chemotherapy administration are proposed.

Adult↗
PubMed1996

Bone marrow transplantation for severe aplastic anemia from genotypically HLA-nonidentical relatives. An update of the Seattle experience.

This report updates the results of marrow transplantation at the Fred Hutchinson Cancer Research Center for patients with severe aplastic anemia whose donors were HLA-nonidentical relatives. Between 1970 and 1993, 40 patients received transplants for severe aplastic anemia from related donors other than HLA genotypically matched siblings. Nine patients (group 1) were conditioned with cyclophosphamide (Cy) at 50 mg/kg for 4 doses and received marrow from phenotypically HLA-matched relatives. With the exception of one accidental death, all patients are alive and disease free 3-18 years after transplantation. Thirty-one patients received marrow from HLA-mismatched relatives who differed by one or more loci. Fifteen of these patients (group 2) received Cy at 50 mg/kg for 4 doses without total body irradiation (TBI) and none survived. Because of failure to sustain engraftment in 9 of 14 evaluable patients in group 2, the regimen for HLA-mismatched patients was changed in 1984 to include Cy at 60 mg/kg for 2 doses and TBI was added at 1200 cGy to increase immunosuppression (group 3). Sixteen patients in group 3 received marrow grafts after failure to respond to immunosuppressive therapy. Eight of the 16 patients in group 3 remain alive without disease between 1.5 and 11.3 years after transplantation. In conclusion, transplants from phenotypically HLA-identical related donors can be carried after Cy alone and results are comparable to those observed with genotypically HLA-identical siblings. Transplants from related donors mismatched for one or more HLA loci require a more intensive conditioning regimen, for example, one containing TBI, to achieve sustained engraftment.

Adolescent↗
PubMed1996

Facilitation of DLA-incompatible marrow grafts by donor-specific serum transferrin?

Studies in mice have shown that donor-specific plasma transferrin (TF) given to the recipient in the peritransplant period facilitates engraftment of marrow from histoincompatible donors. Dogs given 920 cGy of total body irradiation (TBI) and infused with marrow from an unrelated major histocompatibility complex (DLA) different donor generally fail to engraft; only approximately 20% of dogs achieve sustained engraftment. We have now investigated in this model whether the infusion of donor-specific plasma TF would facilitate engraftment. Ten dogs were given TBI, followed at 23 h by an intravenous dose of TF, at 24 h by marrow from the same donor, and another dose of TF at 48 h; six dogs also received postgrafting methotrexate (MTX). Seven dogs (three of four without MTX, four of six with MTX) had sustained engraftment, and three dogs failed to engraft. A single dog given third-party TF failed to engraft. Among five dogs not given TF two achieved sustained engraftment. This pilot study suggests that donor-specific TF facilitates engraftment of DLA-incompatible marrow. Further studies are warranted.

Animals↗
PubMed1996

An anti-CD44 antibody does not enhance engraftment of DLA-identical marrow after low-dose total body irradiation.

920 cGy total body irradiation (TBI) is adequate for consistently successful engraftment of marrow from dog leukocyte antigen (DLA)-identical littermates; however, the dose is inadequate to ensure a marrow graft from DLA-nonidentical unrelated donors. Such mismatched grafts are successful only after 1800 cGy, given in three fractions. While anti-T-cell reagents enhance engraftment of DLA-identical littermate marrow after 920 cGy, they fail to be effective in the DLA-nonidentical setting. However, a monoclonal antibody (mAb) to CD44, S5, was found to be very effective in enhancing engraftment of DLA-nonidentical marrow. The current study asked whether mAb S5 was also effective in the setting of DLA-identical littermate transplants. To this purpose, the TBI dose was lowered to 450 cGy, a dose after which 70% of such grafts failed. Four dogs were treated with antibody S5, 0.2 mg/kg on days -7 through -2 (per previously published protocol), given 450 cGy TBI followed by marrow grafts from their DLA-identical littermates. All four dogs rejected their grafts; two of these died from marrow aplasia, and two survived with endogenous marrow recovery. This result was not statistically significantly different from that in 17, historical (n = 5) and concurrent (n = 12), control dogs where 11 of 17 animals rejected. Even if ten experimental animals were transplanted and all six remaining dogs engrafted, the results still would not have been significantly different from control. This result is in contrast to the successful engraftment promoted by pretreatment with antibody S5 of DLA-nonidentical unrelated dogs, consistent with the notion that different host cells are involved in graft rejection in the two disparate histocompatibility settings.

Animals↗
PubMed1996

The varicella-zoster virus ORF66 protein induces kinase activity and is dispensable for viral replication.

Varicella-zoster virus (VZV) open reading frames (ORFs) 47 and 66 encode proteins that are homologous to a family of eukaryotic serine-threonine kinases. Prior studies showed that the VZV ORF47 protein has kinase activity in vitro and is dispensable for replication in cultured cells. To examine the role of the ORF66 protein during infection, we constructed VZV recombinants that are unable to express either the ORF66 protein (ROka 66S) or both the ORF47 and ORF66 proteins (ROka 47S/66S). VZV unable to express ORF66 grew to titers similar to those of the parental VZV (ROka) in vitro; however, VZV lacking both ORF66 and ORF47 grew to titers lower than those of ROka. Nuclear extracts from ROka 66S- or ROka 47S-infected cells showed a 48-kDa phosphoprotein(s); a phosphoprotein with a similar size was not present in nuclear extracts from ROka 47S/66S-infected cells. To determine the role of the ORF66 protein in the phosphorylation of specific VZV-encoded proteins, we immunoprecipitated known VZV phosphoproteins (ORF4, ORF62, ORF63, and ORF68 proteins) from nuclear extracts of phosphate-labeled cells infected with ROka, ROka 66S, or ROka 47S/66S. Each of the VZV phosphoproteins was phosphorylated to a similar extent in the presence or absence of either the ORF66 protein or both the ORF66 and ORF47 proteins. From these studies we conclude (i) neither ORF66 alone nor ORF66 and ORF47 in combination are essential for VZV growth in cultured cells, (ii) ORF66 either is a protein kinase or induces protein kinase activity during infection, and (iii) the VZV phosphoproteins encoded by ORF4, ORF62, ORF63, and ORF68 do not require either ORF66 alone or ORF66 and ORF47 for phosphorylation in vitro.

Base Sequence↗
PubMed1996

Tacrolimus (FK506) and methotrexate regimens to prevent graft-versus-host disease after unrelated dog leukocyte antigen (DLA) nonidentical marrow transplantation.

We previously reported an synergism between methotrexate and tacrolimus (FK506) in preventing graft-versus-host disease (GVHD) in dogs given DLA-nonidentical unrelated marrow grafts after 9.2 Gy of total body irradiation (TBI). Methotrexate was given at 0.4 mg/kg i.v. on days 1, 3, 6 and 11 and FK506 at 0.15 mg/kg/day i.m. on days 0-8 and 0.5 mg/kg/day orally on days 9-90. Half of the dogs became long-term survivors. A major toxicity was gastrointestinal, and 25% of dogs died with intussusception. The current study addresses the problem of intussusception by making changes in drug doses used. In one group of dogs, FK506 was reduced to 0.075 mg/kg i.m. on days 1-8, while methotrexate was administered per original schedule. In a second group, methotrexate was reduced to a single dose on day 7, while FK506 was either administered per the original or reduced-dose schedule. None of the 17 current dogs developed intussusception, however, all but two dogs died with GVHD (n = 12) or graft failure (n = 3). Only two dogs survived after transient GVHD. Results show that there is little room for maneuvering FK506 or methotrexate doses, and hopes of reducing gastrointestinal toxicity by dose modifications while retaining the ability to prevent GVHD were not fulfilled.

Animals↗
PubMed1996

Delay of radiation-induced decline and recovery of hematopoiesis following treatment with anti-HLA-DR antibody.

A dose of 200 cGy of total-body irradiation (TBI) is nonlethal in dogs: Following a granulocyte nadir in the third week post-TBI, peripheral blood cell counts recover to normal values by about 5 weeks. In the context of studies on a potential role of major histocompatibility (MHC) class II antigens in the regulation of stress hematopoiesis, we tested the effect of anti-MHC class II monoclonal antibodies (mAbs) on hematologic recovery after TBI. Thirteen dogs were given 200 cGy of TBI not followed by marrow infusion. Five received no additional treatment (concurrent controls) and eight were given daily intravenous (IV) injections of anti-class II mAbs H81.9 (anti-HLA-DR; n = 6) or B1F6 (anti-HLA-DR and -DP; n = 2) at 0.6 (n = 4) or 1.2 mg/kg/d (n = 4) on days 0-4 (n = 7) or days 0-9 (n = 1). One control dog died early from an intercurrent infection and four recovered uneventfully. Dogs given mAbs after TBI showed significantly different granulocyte and platelet kinetics. The granulocyte nadir was lower (p = 0.09) and was reached later (p = 0.005), the duration of neutropenia was longer (p = 0.08), and recovery occurred later (p = 0.02) than among controls. Similarly the platelet nadir was lower (p = 0.05), thrombocytopenia lasted longer (p = 0.02), and recovery occurred later (p = 0.02) than among controls. Four of eight mAb-treated dogs died with marrow aplasia. We propose that following irradiation, HLA-DR mediated signals result in terminal differentiation in more mature hematopoietic precursors but interfere with replication or differentiation in early hematopoietic precursors. These observations suggest a role for MHC class II molecules in the regulation of stress hematopoiesis.

Animals↗
PubMed1995

DLA-identical bone marrow grafts after low-dose total body irradiation: effects of high-dose corticosteroids and cyclosporine on engraftment.

Previous studies found that marrow allografts from DLA-identical littermates resulted in survival of 60% of recipient dogs after an otherwise lethal dose of 450 cGy of total body irradiation (TBI), either because of successful allografts or autologous recovery after rejection of the allografts. Forty percent of dogs died with marrow aplasia after allograft rejection. The current study asked whether allogeneic engraftment could be enhanced and survival improved by treating allograft recipients with high doses of corticosteroids or with cyclosporine (CSP), administered either before or after transplantation. Five dogs in group 1 received corticosteroids beginning on day -5 and ending on day 32 after transplant. The starting dose was 12.5 mg of prednisone per kilogram orally twice daily. All five dogs rejected their allografts; three died early with marrow aplasia and two showed endogenous marrow recovery. Nine dogs received CSP from day -6 to day -1 before transplantation at a dose of 20 mg/kg/d intravenously administered in divided doses. All nine dogs rejected the marrow allograft; six died with marrow aplasia and three survived with endogenous marrow recovery. Seven dogs received CSP after transplantation at a dose of 30 mg/kg/d orally from day -1 to day 35. All seven had sustained allografts (two mixed chimeras and five complete donor-type chimeras) and became healthy long-term survivors without graft-versus-host disease. These results extend previous observations and confirm that grafts of marrow from DLA-identical littermates improved survival of dogs exposed to low but otherwise lethal doses of TBI. Additional therapy with high-dose corticosteroids administered peritransplantation and posttransplantation or CSP administered before transplantation neither enhanced the rate of allogeneic engraftment nor improved survival; however, CSP administered after transplantation resulted in successful allografts and event-free survival in all cases.

Adrenal Cortex Hormones↗
PubMed1995

Myelosuppressive conditioning improves autologous engraftment of genetically marked hematopoietic repopulating cells in dogs.

We have studied the role of different conditioning regimens for engraftment of genetically marked hematopoietic repopulating cells in dogs. Peripheral blood (PB) and/or marrow cells collected after treatment with recombinant canine stem cell factor (rcSCF) or cyclophosphamide were transduced in a vector-containing long-term culture system. Three different vector-producing cell lines with similar viral titers were used. In two of them, the neo-containing LN vector was packaged either in the PA317 cell line with an amphotropic murine retrovirus envelope or the PG13 cell line with the gibbon ape leukemia virus (GALV) envelope. The MFG/GC vector produced in PA317 cells contained the human glucocerebrosidase gene. Nineteen dogs received either no conditioning (group A, n = 5), irradiation to both humeri with 1,000 cGy (group B, n = 5), a sublethal dose of cyclophosphamide 40 mg/kg (group C, n = 4), a sublethal dose of 200 or 300 cGy total body irradiation (TBI) (group D, n = 3), or an otherwise lethal dose of 920 cGy TBI (group E, n = 3) before intravenous (groups A, C, D, E) or intramedullary (group B) infusion of the transduced autologous hematopoietic cells. Transduction efficiency of hematopoietic cells at the time of infusion into the animals was similar among the different conditioning groups. Dogs were observed for at least 6 months. PB granulocytes were obtained at least every 3 weeks after transplant and analyzed by polymerase chain reaction for the presence of the transduced genes. The percentages of positive results in dogs more than 4 weeks after transplantation were 0% without conditioning, 5% with local irradiation, 18% with sublethal cyclophosphamide, 33% with sublethal TBI, and 17% with otherwise lethal TBI. Analyzing the influence of conditioning regimens by a generalized estimating equation (GEE) technique, which considered the use of different retrovirus vectors and the number of mononuclear cells infused as potential confounding variables, we found that engraftment of genetically marked repopulating cells was significantly improved (P < .001) in dogs receiving systemic conditioning with either otherwise lethal TBI, sublethal TBI, or sublethal cyclophosphamide compared to dogs with local irradiation only or no conditioning. Within the limitation of the experimental design, these data suggest that myeloablative or myelosuppressive conditioning improves engraftment of genetically marked hematopoietic repopulating cells.

Animals↗