Bone Marrow Transplantation In Rats Research Articles

Bone marrow-derived vasculogenesis leads to scarless regeneration in deep wounds with periosteal defects

Deep skin wounds with periosteal defects, frequently caused by traffic accidents or radical dissection, are refractory. Transplant surgery is frequently performed, but patients are subjected to stress for long operation periods, the sacrifice of donor regions, or several complications, such as flap necrosis or intractable ulcers. Even if the defects are covered, a scar composed of fibrous tissue remains in the body, which can cause itching, dysesthesia, or repeated ulcers because of the lack of distribution of peripheral nerves or hair follicles. Thus, treatments with the aim of regenerating lost tissue for deep wounds with periosteal defects are needed. Here, we show that the use of gelatin sponges (GS), which have been used as haemostatic materials in clinical practice, allowed the regeneration of heterogeneous tissues, including periosteum, skin, and skin appendages, when used as scaffolds in deep wounds with periosteal defects in rats. Bone marrow transplantation in rats revealed the mechanism by which the microenvironment provided by GS enabled bone marrow-derived cells (BMDCs) to form a vascular niche, followed by regeneration of the periosteum, skin, or skin appendages such as hair follicles by local cells. Our findings demonstrated that vascular niche formation provided by BMDCs is crucial for heterogeneous tissue regeneration.

Role of Bone Marrow Transplantation in Reducing the Dangerous Effect of Multi-Walled Carbon Nanotubes or / and Gamma Rays on Male Rats

Aim of the work: this study evaluated the efficacy of bone marrow (BM) transplantation to protect male rats from dangerous effect of multi-walled carbon nanotubes (MWCNTs) or/and γ-irradiation on the hematopoietic and lung tissues. Materials and methods: experimental animals were divided into 8 groups each consist of 6 male albino rats. Control group, BM-injected group, MWCNTs-injected group, 5Gy γ-irradiated group, 5Gy γ-irradiated+ MWCNTs-injected group, MWCNTs-injected+ BM-injected group, 5Gy γ-irradiated+ BM-injected group and 5Gy of γ-irradiated+ MWCNTs-injected + BM-injected group. All the treated animal groups were sacrificed after 28 days of the treatments. Blood components, MDA and GSH levels in the lung tissue were analyzed. The histopathological study in the lung tissue was also recorded. Results: exposure to MWCNTs or/and γ-radiation induced a significant decrease in certain blood components (WBCs, RBCs, Hb content, HCT value and PLT count). Furthermore, a significant elevation in MDA level and a significant decrease in GSH content were detected in the lung tissue. The histopathological changes after exposure of rats to MWCNTs recorded perivasculitis, atelectasis and interstitial pneumonia. Also, γ-radiation represented more collapsed and thickened walls in the alveoli, thickened bronchiolar walls with partial epithelial lining and foci of pulmonary hemorrhage in the lung tissue. The effect of BM transplantation after MWCNTs or/and γ-radiation ameliorated the values of blood components, MDA and GSH levels in the lung tissue. The improvement occurred by BM transplantation in rats treated with MWCNTs or/and exposed to γ-radiation were also recorded. The lung tissue showed numerous alveoli with thin interalveolar septa, alveolar sacs and terminal bronchioles with highly folded mucosa. Conclusion: treatment with BM transplantation improved the most deleterious parameters obtained in the blood and lung tissue of MWCNTs exposed or/and γ-irradiated rats.

Bone Marrow Transplantation Concurrently Reconstitutes Donor Liver and Immune System across Host Species Barrier in Mice

Liver immunopathologic mechanisms during hepatotropic infection, malignant transformation, and autoimmunity are still unclear. Establishing a chimeric mouse with a reconstituted liver and immune system derived from a single donor across species is critical to study regional donor immune responses in recipient liver. Using a strain of mice deficient in tyrosine catabolic enzyme fumarylacetoacetate hydrolase (fah -/-) and bone marrow transplantation (BMT), we reconstituted the donor's hepatocytes and immune cells across host species barrier. Syngeneic, allogeneic or even xenogeneic rat BMT rescued most recipient fah-/- mice against liver failure by donor BM-derived FAH+ hepatocytes. Importantly, immune system developed normally in chimeras, and the immune cells together with organ architecture were intact and functional. Thus, donor BM can across host species barrier and concurrently reconstitutes MHC-identical response between immune cells and hepatocytes, giving rise to a new simple and convenient small animal model to study donor's liver immune response in mice.

The Clinicopathological Characteristics of the Kidney in Acute Graft-versus-Host Disease after Dark Agouti-to-Lewis Rat Bone Marrow Transplantation

Allogeneic hematopoietic and bone marrow cell transplantation causes acute and chronic graft-versus-host disease (GVHD), which is considered a severe side effect. The liver, gut, and skin are well-known primary target sites of acute and chronic GVHD. However, whether the kidney is affected by GVHD remains uncertain. In the present study, we examined the clinical and pathological characteristics of the kidney in acute GVHD in Dark Agouti-to-Lewis rat bone marrow transplantation.

Preclinical analysis of treosulfan in combination with total body irradiation as conditioning regimen prior to bone marrow transplantation in rats

Treosulfan (Treo) and total body irradiation (TBI) demonstrate a high therapeutic activity in treatment of acute leukemia and lymphoma. We investigated the combination of Treo and TBI prior to bone marrow transplantation (BMT) in rats. Female Lewis rats were treated with Treo on 3 consecutive days followed by TBI with either 5 Gy (n = 28) or 7.5 Gy (n = 48). After conditioning animals received 4 × 10E7 bone marrow cells (BC) from female Lewis rats. Additional 16 rats were transplanted with 4 × 10E7 BC and 1.5 × 10E7 spleen T-cells from female Brown-Norway (BN) rats. Animals were examined daily for clinical signs and toxicity was investigated by necropsy and histology in all animals. Gastrointestinal toxicity was the dose-limiting factor of Treo in combination with TBI. The highest tolerable dose of Treo in combination with 7.5 Gy TBI was 3 × 0.5 g/kg and the highest tolerable dose of Treo in combination with 5 Gy TBI was 3 × 0.6 g/kg. Allogeneic BMT from BN donors resulted in engraftment and survival of 12 out of 16 animals. Gastrointestinal toxicity is the dose-limiting factor in the treatment with Treo and TBI. Furthermore, Treo possesses certain characteristics of a radiosensitizer.

Immune tolerance in orthotopic liver transplantation induced by allogenic bone marrow transplantation in rats

Immune tolerance in orthotopic liver transplantation induced by allogenic bone marrow transplantation in rats

Extensive fusion of haematopoietic cells with Purkinje neurons in response to chronic inflammation

Transplanted bone marrow-derived cells (BMDCs) have been reported to fuse with cells of diverse tissues, but the extremely low frequency of fusion has led to the view that such events are biologically insignificant. Nonetheless, in mice with a lethal recessive liver disease (tyrosinaemia), transplantation of wild-type BMDCs restored liver function by cell fusion and prevented death, indicating that cell fusion can have beneficial effects. Here we report that chronic inflammation resulting from severe dermatitis or autoimmune encephalitis leads to robust fusion of BMDCs with Purkinje neurons and formation of hundreds of binucleate heterokaryons per cerebellum, a 10-100-fold higher frequency than previously reported. Single haematopoietic stem-cell transplants showed that the fusogenic cell is from the haematopoietic lineage and parabiosis experiments revealed that fusion can occur without irradiation. Transplantation of rat bone marrow into mice led to activation of dormant rat Purkinje neuron-specific genes in BMDC nuclei after fusion with mouse Purkinje neurons, consistent with nuclear reprogramming. The precise neurological role of these heterokaryons awaits elucidation, but their frequency in brain after inflammation is clearly much higher than previously appreciated.

Immunosuppressive Effects of Multipotent Mesenchymal Stromal Cells on Graft-Versus-Host Disease in Rats Following Allogeneic Bone Marrow Transplantation.

The major obstacle to successful bone marrow transplantation (BMT) is graft versus host disease (GVHD). Multipotent mesenchymal stromal cells (MSC) have shown immunosupressive effects. The aim of this study was to investigate the effect of MSC on the prevention of GVHD in a rat BMT model. We prepared rat GVHD model using allogeneic BMT+4x108 donor splenocyte infusion (DSI). Allogeneic BMT were performed from Spraque Dawley (SD) rats to female Wistar rats by applying 1x108 mononucleer cells (MNC) via tail vein. The recipient animals were conditioned with a myeloablative regimen consisted of 950 cGy total body irradiation prior to BMT. GVHD prophylactic regimen was performed 3 mg/kg/day cyclosporine-A (CsA)+0.25 mg/kg methotrexate (Mtx) IP +1., +3., +6. days. The rats were divided into three control group (CG) and four study group (SG) (n=7). CG-I; only allogeneic BMT+DSI (GVHD model), CG-II; only myeloablative regimen, CG-III; only inspection. GVHD model was performed in all SGs and then SG-I receiving only GVHD prophylactic regimen, SG-II receiving only MSC, SG-III receiving GVHD prophylactic regimen+MSC, SG-IV receiving MSC after GVHD findings developed. Gross (diarrhea, lose weighting, skin findings), histopathological, and immunophenotypical (CD4, CD8, CD25 and plasma IL-2 levels) examinations of GVHD following allogeneic BMT, and the survival analysis of all groups were performed. The survival following allogeneic BMT was significant longer (p<0.05) in SG-I, SG-II and SG-IV than in CG-I (only GVHD model). However, the survival of SG-III (both GVHD prophylactic regimen and MSC administration) was not significant longer than in CG-I (only GVHD model). Gross and histopathological findings of GVHD was significant lower (p<0.05) in SG-I and SG-II than in CG-I (only GVHD model). The expression of CD25 was showed significant increase (p<0.001) in all SGs and CG-I (only GVHD model) than in CG-III (healthy control). Plasma IL-2 levels were showed significant increase in SG-I (p=0.032), SG-II (p=0.018) and SG-IV (p=0.032) than in CG-I (healthy control). This increase was very prominent (p<0.001) in CG-I (only GVHD model) than in CG-III (healthy control). The ratio of CD4/CD8 expression was showed significant lower in SG-I (P=0.008) than in CG-III (healthy control). In contrast, this expression was showed significant increase in SG-II and SG-IV (p=0.014 for both) than in CG-III (healthy control). Finally, clinical use of MSC in both prophylactic and after GVHD developed was as effective as GVHD prophylactic regimen in preventing GVHD. However, MSC combined with GVHD prophylactic regimen was caused strong immunosuppression, and therefore this combination may results in early mortality. This study may form the basis for use of MSC in the prophylaxis and the treatment of GVHD. Our results are encouraging in the use of MSC in GVHD further to clinical trials.

Restoration of bladder contraction by bone marrow transplantation in rats with underactive bladder

We attempted to increase bladder contraction by bone marrow cell transplantation in rats with underactive bladder due to bladder outlet obstruction (BOO). Twelve female rats were anesthetized with halothane to create BOO. After 1 month, the urethral obstruction was removed and they were divided into a transplant group and a sham-operated group (n = 6 each). Bone marrow cells (1 x 10(7) / 0.2 mL) isolated from green fluorescent protein transgenic rats were injected into the bladder wall of the transplant group. Rats from the sham-operated group received injection of culture medium alone. One month after transplantation, isovolumetric cystometry parameters and histological features of bladder were observed as well as intact control rats (n = 6). The amplitude of bladder contractions was larger and the interval between contractions was shorter in the transplant group than the sham-operated group, and there were no differences in these parameters between the transplant group and the control group. Some green fluorescent muscle layers were found in the bladder wall of the transplant group, and these layers were also labeled by anti alpha-smooth muscle actin antibody. These results suggest that transplanted bone marrow cells may improve bladder contractility by differentiating into smooth muscle-like cells.

Sirolimus promotes tolerance for donor and recipient antigens after MHC class II disparate bone marrow transplantation in rats

Mixed chimerism after allogeneic bone marrow transplantation (BMT) promotes immunologic tolerance. Graft-vs-host disease (GvHD) can occur when immunosuppressive control of the graft fails. Here we evaluate the influence of concurrent immunosuppression after irradiation-based induction therapy on development of tolerance and GvHD. Conditioning was performed by different doses of total body irradiation (TBI) in a major histocompatibility complex (MHC) class II disparate rat BMT model. Animals received subsequent immunosuppression with either cyclosporine A (CsA) or sirolimus. Nonresponsiveness toward donor and recipient antigens was demonstrated by development of mixed chimerism and/or GvHD. Administration of 10 Gy of TBI prior to BMT alone was associated with severe GvHD. Induction therapy with 8 Gy of TBI alone led to graft rejection in the long-term. Two weeks of immunosuppression with CsA after 8 Gy of TBI resulted in transient chimerism, but was finally associated with a combination of fatal GvHD and graft rejection. Six gray of TBI with CsA treatment for 14 or 28 days caused only mild GvHD, but did not lead to stable chimerism. In contrast, treatment with sirolimus was associated with stable chimerism after 8 Gy of TBI (14-day course) and 6 Gy of TBI (28-day course) accompanied by a low incidence of GvHD. In contrast to CsA, sirolimus facilitates development of tolerance after MHC class II disparate BMT and irradiation-based conditioning, with a low risk of GvHD. Therefore, sirolimus has promising characteristics for inclusion in immunosuppressive protocols.

Reduced graft-versus-host disease-inducing capacity of T cells after activation, culturing, and magnetic cell sorting selection in an allogeneic bone marrow transplantation model in rats.

Graft-versus-host disease (GvHD), a major complication of allogeneic bone marrow transplantation, has been ascribed to mature T cells in the graft. Because T cells play an important role in engraftment of the bone marrow and decrease the probability of relapse of leukemia, a treatment strategy was developed to preserve the benefits of T cells in the graft and to control the severe complications of GvHD. This can be accomplished by the genetic modification of donor T cells with a suicide gene that allows their selective in vivo elimination and subsequently the abrogation of GvHD. For clinical benefit the alloreactivity of herpes simplex virus thymidine kinase (HSV-TK) gene-transduced T cells should be retained. Therefore, we investigated the influence of gene transduction and the selection procedure on T cells. We demonstrated that activation and culturing of T cells reduce their capacity to induce lethal GvHD in an allogeneic rat bone marrow transplantation model. Furthermore, positive immunomagnetic selection of gene-transduced T cells resulted in loss of the GvHD-inducing capacity of HSV-TK(+) T cells directly after MACS (magnetic cell sorting) selection; this loss could be recovered by a 1-day expansion of the selected T cells. No effect on alloreactivity was observed to be caused by the gene transduction procedure. Our study resulted in the development of an optimized culture and gene transduction protocol with preservation of T cell alloreactivity. Treatment of transplanted rats with ganciclovir resulted in a rapid reduction in the number of HSV-TK(+) T cells in the peripheral blood and in increased survival of the animals.

Long-term survival of cardiac xenografts in fully xenogeneic (mouse → rat) bone marrow chimeras

Background. The shortage of human hearts remains a major barrier to the efficacy of heart transplantation for the treatment of end-stage heart disease. One potential solution to the supply problem would be the use of hearts from nonhuman donors (xenografts). We have established a model of mouse to rat xenogeneic bone marrow chimerism, and in this study we have hypothesized that such chimeric rats will accept both donor and recipient specific heart grafts while rejecting third-party mouse and rat grafts. We also investigated humoral responses in naı̈ve and chimeric rats with and without donor murine cardiac grafts. Methods. Recipient Lewis rats (n = 22) were given 1100 cGy lethal total body irradiation and the same day received 300 × 10 6 donor B10.BR mouse bone marrow cells intravenously. Peripheral blood of surviving rats (n = 18) was typed at 4 weeks and then monthly thereafter. Donor and recipient specific and third-party heterotopic heart transplantations were performed at 6 to 8 weeks after reconstitution with bone marrow. Results. Multilineage bone marrow chimerism was produced in all experimental animals with complete replacement of recipient marrow by donor cells. Murine donor and rat recipient strain hearts transplanted in chimeric rats survived indefinitely. Third-party rat and mouse hearts were rejected, though at a slower rate than bone marrow matched naı̈ve controls. High levels of antimouse antibodies were detected in rats with rejected hearts. These antibodies were absent in chimeric animals with long-term surviving heart grafts. Conclusions. Long-term multilineage bone marrow chimerism can be produced in a mouse → rat bone marrow transplant model. Long-term survival of donor specific and recipient specific vascularized cardiac grafts can be produced in these chimeric animals. These animals are clinically normal but show signs of subclinical immunosuppression regimen as they reject third-party hearts later than naı̈ve animals. Our results suggest that antibodies also play a significant role in concordant xenograft rejection, and induction of bone marrow chimerism can overcome this barrier.

MC1288, a vitamin D analog, prevents acute graft-versus-host disease in rat bone marrow transplantation.

The major obstacle to successful bone marrow transplantation (BMT) is graft-versus-host disease (GVHD). Vitamin D analogs have shown their efficacy in solid organ transplantation. The purpose of this study was to investigate the suitability of a novel vitamin D analog, MC1288, in the prevention of acute GVHD in a rat BMT model. Allogeneic BMT were performed from Lewis to BN rats (n = 18). The animals were divided into four groups: an untreated control group, MC1288, cyclosporin A (CsA), and MC1288 + CsA-treated groups. Rats were harvested for histology and immunohistochemistry on day 20 after BMT. Histological changes for GVHD in liver, skin, and spleen were scored. Positivity in immunostaining was quantified as the number of positive cells/high power field. Treatment with MC1288 decreased clinical signs of GVHD compared with untreated or CsA-treated rats. Histological manifestations of GVHD, expressed as mean total increment, were significantly lower (1.4 +/- 0.5) in MC1288 than in untreated (5.0 +/- 1.6) or CsA (3.5 +/- 1.0) groups. Combining MC1288 and CsA further improved histology (1.1 +/- 0.6). The expression of CD4, CD8, MHC class II, interleukin-2 receptor, nitric oxide 2, and NKR-P1A (NK cells) positivity was significantly decreased in the liver and skin of BMT rats by MC1288. MC1288 was effective in preventing clinical and histological signs and symptoms of GVHD. This novel vitamin D analog could be used as an immunomodulating agent in BMT.

ESTABLISHMENT OF FULLY XENOGENEIC (MOUSE ??? RAT) BONE MARROW CHIMERAS: EVIDENCE FOR NORMAL DEVELOPMENT AND CLONAL DELETION OF MOUSE T CELLS1

Xenotransplantation is a potential solution to the critical shortage of transplantable organs. However, conventional immunosuppressive agents do not control the vigorous cellular and humoral rejection across species disparities. The induction of donor specific tolerance via bone marrow chimerism may be a method to avoid xenograft rejection. In xenogeneic chimeras, T cell repertoire selection plays an important role in the induction of tolerance. Until now a model of mouse-->rat multilineage chimerism has not been reported. This study reports the establishment of fully xenogeneic mouse-->rat multilineage chimeras and evaluates the role of T cell development and repertoire selection in tolerance induction in a xenogeneic environment. Recipient rats were irradiated at a dose of total body irradiation ranging between 800-1100 cGy and injected with 120-300x10(6) donor mouse bone marrow cells. Chimeras were typed for engraftment at 4 weeks and then monthly thereafter. T cell repertoire was evaluated in chimeras using two-color flow cytometry and monoclonal antibodies directed against the variable portion of the beta chain of the T cell receptor. Fully xenogeneic multilineage bone marrow chimerism was produced in a mouse-->rat model by using ablative radiation and a high dose of donor cells. Mouse T cells develop in a phenotypically normal fashion in chimeric rats and the host rat is capable of deleting T cells that are reactive to the donor mouse strain. Long-term multilineage bone marrow chimerism can be produced in a mouse-->rat bone marrow transplant model. Mouse T cells develop in a phenotypically normal fashion and negative selection of specific T cell receptor-Vbeta occurs in a xenogeneic environment in a predictable fashion paralleling that for syngeneic or allogeneic transplantation.

MIXED XENOGENEIC CHIMERISM AND TOLERANCE III

Previously, we reported that transplantation of rat bone marrow into lethally irradiated (950 rads) mouse recipients results in stable xenogeneic (rat-->mouse) chimerism and confers donor-specific transplantation tolerance for subsequent or simultaneous islet xenografts. For potential clinical application of chimerism to induce tolerance, it would be important to avoid the morbidity and mortality associated with lethal conditioning. Recently, we established a model to achieve durable multilineage xenogeneic chimerism using a nonlethal cytoreductive approach. We report here for the first time that donor-specific rat islet xenografts placed coincident with the bone marrow transplant are permanently accepted by nonlethally conditioned recipients. All recipients conditioned with 700 cGy of total body irradiation and transplanted with 40 x 10(6) F344 rat bone marrow cells repopulated as mixed donor/host chimeras. The chimeras exhibited permanent acceptance of donor islet xenografts, since donor-specific F344 (Rt1A1) rat islet xenografts were significantly prolonged (median survival time > 110 days), while MHC-disparate third-party WF (Rt1Au) rat islets were prolonged but rejected (median survival time = 33.2 days). The islets were functional to maintain normoglycemia and regulated in function to respond to an intraperitoneal glucose challenge. These data suggest that tolerance to donor-specific islet xenografts placed coincident with bone marrow transplantation can be achieved after nonlethal conditioning.

Prophylaxis of Bone Marrow Transplant Nephropathy with Captopril, an Inhibitor of Angiotensin-Converting Enzyme

Chronic renal failure occurs in about 20% of long-term survivors treated with bone marrow transplant (BMT) regimens that include total-body irradiation (TBI); this syndrome is called BMT nephropathy. In a previous study in a syngeneic rat BMT model it was shown that captopril (an inhibitor of angiotensin-converting enzyme) could be used to treat experimental BMT nephropathy. Current studies were designed to determine whether captopril could also be used to prevent BMT nephropathy. Rats received 14 to 18.5 Gy TBI in six fractions over 3 days followed by syngeneic BMT. Seven days before TBI half the rats were started on captopril (500 mg/liter in the drinking water). Blood urea nitrogen, ratios of urine protein to creatinine, serum creatinine, and blood pressure were used to assess renal function. In animals receiving TBI alone, BMT nephropathy developed 3 to 6 months after transplant. At 6 months after TBI, captopril-treated animals had lower systolic blood pressure and better-preserved renal function than animals receiving TBI alone, with dose-modifying factors of about 1.3. The captopril treatment had no effect on bone marrow ablation by TBI. Captopril appears to be safe and effective in the prophylaxis of BMT nephropathy.

Treatment of radiation nephropathy with ace inhibitors

Purpose : A previous study showed that radiation nephritis could be treated with captopril, an angiotensin-converting enzyme inhibitor. These studies were designed to determine whether other angiotensin-converting-enzyme inhibitors would be effective, whether captopril would inhibit the development of the histopathologic lesions typical of radiation nephritis, and whether captopril could be used to treat the nephropathy observed in bone marrow transplant recipients conditioned with total body irradiation. Methods and Materials : In radiation nephritis studies, rats were given 17–27 Gy bilateral renal irradiation in 5 fractions. Six months after irradiation animals were stratified by blood urea nitrogen and assigned to no treatment, or treatment with captopril (500 mg/l) or enalapril (50 mg/l) in the drinking water. A subset of animals was sacrificed for histopathology after 3 months; the remaining animals continued on drugs for 7 months. In the bone marrow transplant nephropathy study, rats receivd 14–17 Gy total irradiation in 6 fractions over 3 days followed by syngeneic marrow transplant. Six months after irradiation, animals were stratified by blood urea nitrogen and assigned to no treatment, or treatment with captopril (500 mg/l). Animals remained on drugs for 6 months. In all studies animals were followed with periodic function tests. Results : In the radiation nephritis study, survival and renal function were significantly enhanced by both captopril and enalapril, but there were no significant differences between the drugs. The histopathologic severity of the lesions of radiation nephritis correlated with the degree of renal dysfunction; and in irradiated animals with equal initial azotemia, captopril-treated rats developed less severe renal lesions. Finally, captopril also prolonged survival and preserved renal function in this rat bone marrow transplant nephropathy model. Conclusion : Angiotensin-converting-enzyme inhibitors are an effective treatment for both radiation nephritis and bone marrow transplant nephropathy.

Suppression of graft-versus-host disease by succinyl acetone in a rat allogeneic bone marrow transplantation model.

The efficacy of succinyl acetone (SA, 4,6-dioxoheptanoic acid) was explored in the allogeneic rat bone marrow transplant model of graft-vs.-host disease. Lethally irradiated Wistar Furth rats receiving Fischer 344 allogeneic bone marrow and spleen cells developed severe GVHD, resulting in mortality at 25-45 days posttransplant. Treatment for 14 days with 250 mg/kg/day of SA by Alzet osmotic pumps implanted subcutaneously 3 days before cell transfer prevented GVHD and produced long-term survivors that were allogeneic hematopoietic chimeras. SA doses below 250 mg/kg/day and treatment for less than 14 days were less efficacious. Initiation of SA therapy could be effectively delayed up to 7 days after BMT. Pharmacokinetic studies with i.v. bolus administration in normal CD rats revealed a plasma mean residence time that increased with dose and a systemic clearance that decreased with dose. Three dose-dependent half lives were apparent (ca. 7-18 min, 0.8-3 hr, and 12 hr). The s.c. bioavailability was ca. 82%. Relatively constant plasma SA levels were obtained with s.c. Alzet osmotic pumps, indicating no change in clearance with continuous exposure. Allogeneic BMT exerted no major influence upon SA clearance. These studies show that SA is a robust therapeutic agent that suppressed GVHD in the allogeneic rat BMT model under a variety of circumstances.

The hematopoietic system influences odor specificity in mice and rats.

The change in strain-specific urine odors which appears after bone marrow transplantations was examined in mice and rats in order to demonstrate an influence of the hematopoietic system on urinary chemosignals. Four rats were trained in an olfactometer to discriminate two allogeneic mouse or rat strains via their urine odors. Urine samples obtained from two inbred strains of mice, from two inbred strains of rats, from allogeneic reconstituted mice, and from semiallogeneic reconstituted rats were combined in a number of 'transfer of training' tests. Results confirm findings that the hematopoietic system influences odor specificity in mice. For the first time a change of urinary chemosignals after bone marrow transplantation in rats was demonstrated by using semiallogeneic reconstituted rat chimeras.

Systemic monoclonal antibody therapy for eliminating minimal residual leukemia in a rat bone marrow transplant model

In an animal bone marrow transplant (BMT) model that mimics the human clinical condition, we evaluated the effectiveness of monoclonal antibody (MoAb) therapy in eliminating minimal residual disease (MRD) in a leukemic host. Leukemic rats were prepared with marrow ablative but noncurative doses of busulfan (BU) and cyclophosphamide (CY). Two days after syngeneic BMT, rats were treated with MoAb. Although all control rats died of leukemia relapse, 58% of those treated with MoAb were cured without any demonstrable effect on the rate of peripheral blood leukocyte recovery. Furthermore, the level of complement, an important effector in suppressing leukemia proliferation in the normal rat, was not adversely affected by BU/CY, BMT and MoAb. Thus, we demonstrated in an animal model that MoAb therapy may be a useful, nontoxic adjunct to high-dose chemotherapy and BMT in eliminating MRD.