Fast lymphoid reconstitution after vascularized bone marrow transplantation in lethally irradiated rats

BACKGROUND

Bone marrow (BM) transplantation for treatment of hematological and solid malignancies is routinely carried out in conjunction with radio- and chemotherapy. Many patients achieve complete remission of the malignant process; however, their lymphohematopoietic recovery remains in most cases incomplete. This is probably due to the functional changes in the recipient BM stromal cells subsequent to myeloablative therapy. Transplantation of BM hematopoietic cells in a spatial relationship with stromal cells would give an insight into the kinetics of hematological repopulation of the recipient. The aim of this study was to investigate the lymphopoietic reconstitution of irradiated rats after vascularized bone marrow transplantation (VBMT) in comparison with i.v. bone marrow cell (BMC) infusion.

METHODS

Lewis rats were totally irradiated with 8Gy and repopulated with syngeneic BMC introduced i.v. or in orthotopic hind limb graft. Ten days after irradiation and BMC graft BM, peripheral blood (PB) and mesenteric lymph nodes (MLN) were collected. The yield and the phenotype of cells were analyzed.

RESULTS

VBMT brings much higher cell repopulation of BM cavities of lethally irradiated rats than BMC infusion. Orthotopic hind limb graft promotes also rapid lymphocyte replenishment of PB and MLN of lethally irradiated syngeneic recipients. The population rate of BMC, PB lymphocytes, and MLN lymphocytes was higher after VBMT than BMC injection in suspension. The percentage of T and B lymphocytes in PB and MLN on day 10 after VBMT was comparable with control values. Reconstituted PB lymphocytes showed two subsets of CD4+ cells: "bright" and "dull." All CD4+ cells in PB lymphocytes of i.v. BMC infused recipients expressed low level of these molecules ("dull" subset).

CONCLUSIONS

The results of our studies indicate that the presence of stromal cells in their close relationship with stem cells is essential for the fast lyphohematopoietic repopulation of irradiated recipients. The population of CD4+dull cells may represent immature cells. These cells were not found in MLN of VBMT rats. All MLN CD4+ cells represented the "bright" subset, what suggests that the process of cell maturation may occur in the lymphoid organs.

Clinical course of concomitant Hbv and Hcv infection in renal allograft recipients

We evaluated the impact of concomitant infection with Hepatitis B virus (HBV) and Hepatitis C virus (HCV) on the clinical course after renal transplantation (Tx). In 335 patients (pts) transplanted between 1991 and 1993 we found 30 (9%) recipients who were positive for Hepatitis B surface antigen (HBsAg) (ELISA, Organon) and anti-HCV antibodies (immunoblot assay Lia Tek) preTx. Chronic liver disease (CLD) (two-fold or greater increase in serum ALT and AST levels for at least six months) developed in 40.7% coinfected pts as compared to 24.4% and 25.7% pts infected only with HCV or HBV, respectively. Maintenance immunosuppression consisted of P + Aza + CsA, mean follow-up time was 28 +/- 15 months. The mean time of the onset of CLD was 3.0 months (range: 1-18 months) after Tx. Percutaneous liver biopsy performed in 5 CLD pts revealed chronic active hepatitis (CAH) in 4 and chronic persistent hepatitis (CPH) in 1 pt. Four pts who had CAH and were positive for HCV RNA (RT PCR) in serum and for HBcAg in liver tissue, received interferon-alpha therapy for 6 months. Clinical improvement of liver function was observed in all of them, but none cleared HBsAg or HCV RNA. One pt lost his graft due to acute rejection. Concomitant infection with HBV and HCV is associated with the high risk of development of CLD early after Tx. We recommend that pretransplant evaluation of both anti-HCV and HBsAg positive pts should include liver biopsy to exclude potential recipients with CAH.

Microchimerism following allogeneic vascularized bone marrow transplantation--its possible role in induction of posttransplantation tolerance

We have noticed that bone marrow transplanted in a vascularized limb graft providing a continuous supply of donor BMC may prolong the survival time of skin graft from the same donor. The question arises whether the raised microchimerism plays a role in the prolonged survival of skin allograft. The aim of the study was to follow the development of microchimerism after allogeneic vascularized bone marrow transplantation (VBMTx) concomitantly with the rejection processes of transplanted skin. The BN rats served as donors and LEW rats as recipients of VBMTx and free skin flap allograft. Hind limb was transplanted followed by a full-thickness skin graft on the dorsum. Cellular microchimerism was investigated in recipients of VBMTx and skin grafts in blood, spleen, mesenteric lymph node and bone marrow with monoclonal antibody OX27 directed against MHC class I polymorthic RTI on BN cells and quantitatively analysed in FACStar. In VBMTx group free skin flap survived 70 days after weaning of CsA. Intravenous infusion of BMC in suspension equivalent to that grafted in hind limb did not prolong skin graft survival after cessation of CsA therapy. Donor-derived cells could be detected in VBMTx recipients as long 70 days after wearing of CsA but not in recipients of i.v. suspension BMC grafting.

Predictor of transplanted kidney deterioration following pregnancy--daily urine protein loss or serum creatinine concentration?

Increasing number of female kidney recipients deciding to born a baby makes us to investigate the impact of pregnancy on graft survival. The aim of study was to find the parameter that would have the predictive value for graft function following delivery. Scr and P in 33 pregnant renal allograft recipients (mean age 27.1 +/- 6.1 yrs) treated with pred + aza + CsA were studied for 6 mo before, during and 6 mo following delivery. As measured only by Scr graft function was stable in all pts (1.4 +/- 0.05 mg/dl). Significant rise in Scr following pregnancy was found in 6 of 33 pts. This "unstable" group was compared with 27 patients with "stable" despite pregnancy graft function. Proteinuria, but not Scr differentiated groups prior to pregnancy. The estimation of P prior to conception seems to be more potent parameter to predict kidney graft deterioration following pregnancy than Scr alone. Increase in P during and following pregnancy in "unstable" pts may reflect the acceleration of subclinical (not yet manifested with rise of Scr) chronic graft rejection due to pregnancy-induced hiperfiltration.

Body distribution of syngeneic and allogeneic cells from vascularized bone marrow graft

In the previous studies we showed that vascularized bone marrow graft (VBMtx) in transplanted rat hind limb brings about complete repopulation of syngeneic recipient BM cavities and lymphoid organs within 10 days. Transplantation of an equivalent number of bone marrow cells (BMC) in suspension did not produce repopulation until day 30. In this study we present data on transplantation of allogeneic VBM and compare them with those obtained in a syngeneic combination. In the LEW or BN to LEW combination BM cells were labelled with 51Cr, injected i.v., 24 h later the hind limb was amputated and transplanted to a LEW rat. BM cells emigrated from the transplanted limb to the recipient and distributed in BM cavities and lymphoid tissues. In the LEW to LEW combination the level of radioactivity in recipient tibia was after 24 h 0.85, in spleen 2.43, in mesenteric lymph node 0.52%/g of tissue, whereas in the BN to LEW model it was 0.11, 1.83 and 0.15%, respectively. The calculated numbers of BM cells which populated recipient tissues were 8-10-times lower in the allogeneic compared with syngeneic combination. This was probably due to the nonspecific elimination of some subsets of BM cells (allogeneic BMC cytotoxicity). Administration of anti-asialo GMI antiserum to the recipient abrogated the cytotoxic effect. Taken together, major differences in kinetics of seeding and repopulation of BMC from VBMTx were found. Elimination of recipient NK cells with AAGMI antiserum attenuated the nonspecific cytotoxic effect. This protocol allows protection of the grafted BMC and increases the efficacy of the transplant.

Reconstitution of lymphoid tissue after vascularized bone marrow transplantation

We reported previously that vascularized bone marrow transplantation (VBMT) in an orthotopic hind limb graft brings about complete repopulation of bone marrow cavities in lethally irradiated syngeneic recipients within 10 days. Intravenous infusion of an equivalent volume of bone marrow cell suspension was evidently less effective. The purpose of this study was to investigate the reconstitution of immunocompetent compartments of lethally irradiated syngeneic rats after VBMT. Lewis rat hind limbs were transplanted orthotopically into irradiated recipients. Ten days after irradiation and bone marrow transplantation, bone marrow, mesenteric lymph nodes and sera from rats were harvested. Responsiveness of mesenteric lymph node lymphocytes (MLNL) to mitogens and lymphocyte proliferation in the presence of sera and bone marrow cell (BMC) culture supernatants was measured. Our studies have shown that vascularized bone marrow transplantation brings about rapid replenishment of lymphoid organs of lethally irradiated syngeneic recipients. The repopulating subsets were fully responsive to mitogens. Sera from reconstituting rats had no evident effect on proliferation of mature lymphocytes. Intravenous infusion of BMC in suspension, in a number equivalent to that grafted in hind limb transplant, was less efficient in reconstituting lymphoid tissue.

Long-term results of treatment of chronic hepatitis B, C and D with interferon-alpha in renal allograft recipients

The aim of this study was to evaluate the efficacy and safety of interferon-alpha (IFN-alpha) therapy of chronic hepatitis B, C and D (HBV, HCV and HDV, respectively) in renal transplant recipients. A group of 42 patients (30 males, 12 females, mean age 38 years) with documented viraemia and chronic active hepatitis (CAH) were studied, of whom 1 had HBV infection alone, 11 had HCV infection alone, 3 had HBV and HDV infection concomitantly, 12 had HBV and HCV infection concomitantly, and 2 had HBV, HCV and HDV infection concomitantly. Patients received 3 MU IFN-alpha three times weekly for 6 months. After IFN-alpha therapy, 18 patients (43%) achieved normal alanine aminotransferase (ALT) activity and a partial response was observed in 12 (29%) patients. Two patients relapsed (one with HCV and one with HBV + HCV infection) immediately after the cessation of IFN-alpha therapy. Repeated liver biopsy was performed in 16 patients after 6-24 months of therapy and revealed progression to cirrhosis in five patients, remission in two and stable disease in nine. None of the patients cleared HCV RNA, four patients cleared HBeAg (two also HDV), and one both HBV and HCV. Five patients died during IFN-alpha therapy (one as a consequence of liver failure), and four died during the 6 months after therapy (two as a consequence of liver failure). During IFN-alpha therapy renal allograft function remained stable in 31 patients and acute rejection episodes occurred in 7, of whom 5 lost their graft and all had experienced rejection episodes before. In 16 patients normalization of ALT continued during long-term follow-up (median 22 months, range 0-84 months). IFN-alpha seemed to be moderately effective in the treatment of chronic HBV or HCV infections, but cannot be recommended for recipients infected with both HBV and HCV.

Cyclosporine A blood concentration during pregnancy in renal allograft recipients

Pregnancy-induced changes increase hazards associated with cyclosporine (CsA) treatment. Blood CsA trough levels (C0) were estimated in 15 pregnant renal allograft recipients treated with prednisolone + CsA + azathioprine using the TDx Abbott fluorescent polarization immunoassay. Despite therapeutical dose levels of CsA administered during pregnancy (3.52-3.67 and 3.59 mg/kg body weight in the first, second, and third trimesters, respectively), C0 significantly decreased (first trimester 130.8 +/- 36.9, second 92.0 +/- 32.7, and third 99.0 +/- 36.9 ng/ml). The mean increase of patient's body weight in mid-pregnancy was 3.0 +/- 2.19 kg and was associated with a significant (P < 0.05) fall in a hematocrit value (from 42 +/- 4.9% prior to pregnancy to 34 +/- 6% at the 20th week). We postulate that C0 concentration does not reflect the true exposure to CsA as no episodes of acute graft rejection were observed during pregnancy.

Long-term results of treatment of chronic hepatitis B, C and D with interferon-alpha in renal allograft recipients

The aim of this study was to evaluate the efficacy and safety of interferon-alpha (IFN-alpha) therapy of chronic hepatitis B, C and D (HBV, HCV and HDV, respectively) in renal transplant recipients. A group of 42 patients (30 males, 12 females, mean age 38 years) with documented viraemia and chronic active hepatitis (CAH) were studied, of whom 1 had HBV infection alone, 11 had HCV infection alone, 3 had HBV and HDV infection concomitantly, 12 had HBV and HCV infection concomitantly, and 2 had HBV, HCV and HDV infection concomitantly. Patients received 3 MU IFN-alpha three times weekly for 6 months. After IFN-alpha therapy, 18 patients (43%) achieved normal alanine aminotransferase (ALT) activity and a partial response was observed in 12 (29%) patients. Two patients relapsed (one with HCV and one with HBV + HCV infection) immediately after the cessation of IFN-alpha therapy. Repeated liver biopsy was performed in 16 patients after 6-24 months of therapy and revealed progression to cirrhosis in five patients, remission in two and stable disease in nine. None of the patients cleared HCV RNA, four patients cleared HBeAg (two also HDV), and one both HBV and HCV. Five patients died during IFN-alpha therapy (one as a consequence of liver failure), and four died during the 6 months after therapy (two as a consequence of liver failure). During IFN-alpha therapy renal allograft function remained stable in 31 patients and acute rejection episodes occurred in 7, of whom 5 lost their graft and all had experienced rejection episodes before. In 16 patients normalization of ALT continued during long-term follow-up (median 22 months, range 0-84 months). IFN-alpha seemed to be moderately effective in the treatment of chronic HBV or HCV infections, but cannot be recommended for recipients infected with both HBV and HCV.

Tolerance induction following allogeneic vascularized bone marrow transplantation--the possible role of microchimerism

We have noticed that bone marrow transplanted in a vascularized limb graft, providing a continuous supply of donor bone marrow cells (BMC), may prolong the survival time of a skin graft from the same donor. The question arises whether the microchimerism raised plays a role in the prolonged survival of skin allografts. The aim of the study was to follow the development of microchimerism after allogeneic vascularized bone marrow transplantation (VBMTx) concomitantly with the rejection process of transplanted skin. Brown Norway (BN) rats served as donors and Lewis rats as recipients of VBMTx and free skin flap allografts. A hind limb was transplanted, followed by a full-thickness skin graft on the dorsum. Cellular microchimerism was investigated in recipients of VBMTx and skin grafts in blood, spleen, mesenteric lymph node, and bone marrow with the monoclonal antibody OX27 directed against MHC class I polymorphic RT1 on BN cells and quantitatively analyzed in a FACStar. In the VBMTx group, the free skin flap survived 70 days after weaning off cyclosporine A (CsA). An intravenous infusion of BMC in suspension equivalent to that grafted in the hind limb did not prolong skin graft survival after cessation of CsA therapy. Donor-derived cells could be detected in VBMTx recipients as long 70 days after weaning off CsA but not in recipients of i.v. suspension BMC grafting.

Lymphocyte interactions with extracellular matrix proteins and endothelium in renal allograft recipients

Recent data indicate that extracellular matrix (ECM) proteins can provide costimulatory signals during the process of T cell activation. Those proteins accumulate in situ during allograft rejection; therefore, it may be expected that local ECM: T cell interactions may be relevant in the immunopathology of rejection. T cell adhesion from allograft of recipients with stable renal function (RAR-S) and patients with biopsy-proven chronic rejection (RAR-CH) to ECM proteins (collagen type IV, fibronectin, elastin) was measured. Furthermore, T cell: endothelial interactions in vitro were studied. Adhesion of PHA-activated T cells from both groups of allograft recipients to fibronectin, collagen type IV and elastin was significantly lower than in healthy blood donors. Moreover, similar pattern of activity was observed when T cell attachment to resting and activated endothelium was studied. There were no significant differences in the number of circulating CD45RO and CD4 positive T cells. We observed a higher (although not significantly) adhesion of the T cells to resting human dermal microvascular endothelial cells (HMEC) in the chronic stages of rejection, which can suggest that the immunosuppressive protocol used in the treatment of chronic rejection is insufficient to control immunopathologic phenomena occurring in that process. Therefore, it may be argued that too low immunosuppression can be one of the factors responsible for the development of this complication.

[The effect of hypolipidemia treatment on the function of kidney transplanted from cadavers]

The high prevalence of hypercholesterolemia (HCh) in kidney transplant recipients probably contributes to the high cardiovascular mortality of these patients. Additionally, HCh is a contributing factor to the progression of renal failure. We conducted a prospective, randomised study with low dose Lovastatin in 42 kidney transplant recipients during 32 weeks, focusing on side effect and kidney function 42 consecutive patients with kidney transplanted in our Institute, with stable renal function (creatinine level < 160 mmol/l) treated with ciclosporine, azathioprine, prednisone were enrolled for the study (regardless of the initial cholesterol level). Every second patient was given Lovastatin 20 mg/night. In the Lovastatin group total cholesterol (TC) and LDL concentration were significantly lower after 6 months of treatment (TC was reduced from 242.5 +/- 12.8 to 220 +/- 15.4 mg/dl, p < 0.05) in Lovastatin group whereas in control group it increased nonsignificantly. Similarly LDL in Lovastatin group decreased from 140.0 +/- 7.0 to 121.3 +/- 10.8 mg/dl, p < 0.02 whereas in control group it increased from 143.6 +/- 5.4 to 169.9 +/- 10.3 mg/dl, p < 0.01. HDL and trigliceride concentrations were unchanged. The Lovastatin treatment did not results in more adverse events than the placebo treatment. Notably, the tendency to increase creatinine level in Lovastatin group was observed from 1.59 +/- 0.17 to 1.74 +/- 0.22 in Lovastatin group versus 1.89 +/- 0.22 to 2.21 +/- 0.35 mg/dl (NS). Low dose Lovastatin treatment seems to be safe and efficient cholesterol-lowering procedure. However we did not observe beneficial effect on kidney graft function.