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In vivo location of intramyocardial implanted 111In-oxine labeled mesenchymal stem cells: Assessement with dual energy pinhole 99mTc-Sestamibi SPECT in a rat model of myocardial infarction
S136
Abstracts
The Journal of Heart and Lung Transplantation February 2005
287 RENAL BENEFIT OF RAPAMYCIN IN PEDIATRIC HEART TRANSPLANT PATIENTS I.C. Balfour, S.W. Srun, E.G. Wood, C.W. Belsha, D.L. Marshall, B.R. Ferdman, Department of Pediatrics, Saint Louis University School of Medicine, Saint Louis, MO Background: Calcineurin inhibitors (CNI) are effective in preventing rejection in recipients of solid organ transplants, but these agents are nephrotoxic. Rapamycin (RAPA) when used in conjunction with CNI, allows a lower dose of CNI to be used, potentially reducing renal damage. Pediatric heart transplant patients (Pts) were studied to determine if their renal function improved after initiating RAPA. Methods: RAPA was started in 15 pts with reduced (10) or no CNI (5). We studied renal and other parameters before and after RAPA was started. Pts were 4.1 ⫾ 5.7 yrs old (mean ⫾ 1 standard deviation) at transplant (median 0.4 yrs) and 10.3 ⫾ 4.6 yrs old when switched to RAPA (median 9.2 yrs), 10 were male. Indications for RAPA were worsening renal function (10), to improve adherence (2), change in protocol (2), post transplant lymphoproliferative disease (1). The pre and post RAPA data were compared using a paired-samples T-test. Results: At 30 days after RAPA the calculated creatinine clearance (Schwartz formula) increased from 88 ⫾ 28 ml/min/1.73M2 to 105 ⫾ 27, p .008. None of the patients had rejection after RAPA.
Pre-RAPA 30 days post RAPA p
BUN
Cr
Hb
WBC
Kⴙ
Mgⴙⴙ
27.1 ⫾ 12.4 18.6 ⫾ 11.1*
1.0 ⫾ 0.5 0.8 ⫾ 0.3**
11.5 ⫾ 1.7 12.0 ⫾ 1.3
5.9 ⫾ 2.1 7.7 ⫾ 3.5
5.2 ⫾ 0.5 4.5 ⫾ 0.6***
1.6 ⫾ 0.2 1.3 ⫾ 0.4****
*0.014
**0.019
***0.010
****0.049
Conclusion: Renal function appears to improve in the short term after starting RAPA and lowering CNI dose. RAPA may be beneficial in preserving renal function in pediatric heart transplant pts. 288 INTRAVENOUS STEROIDS DO NOT INCREASE PERIOPERATIVE AIRWAY COMPLICATION RISK IN PEDIATRIC LUNG TRANSPLANT PATIENTS J. Nigro,1 M.V. Horn,1 V.A. Starnes,1 M.L. Barr,1 M.S. Woo,1 1 Cardiothoracic Surgery, Childrens Hospital Los Angeles, Los Angeles, CA Does IV steroid use during the 1st week after lung transplant surgery increase the risk of airway complications? Some centers advocate using induction therapy and then holding steroids from Day 2 thru Day 7. However, use of induction therapy carries increased infection risk and expense. To determine if airway complications (airway dehiscence) are associated with IV steroid use in the immediate post-transplant period, we performed a retrospective review of all lung transplantations performed at our center. Heart-lung transplant recipients were excluded from analysis. Data collected: pt age, primary diagnosis, type of transplant (cadaveric or living donor), airway culture results prior to transplant, occurrence of airway complications (dehiscence, poor wound healing, prolonged air leak, etc), pre-transplant use of steroids (dose /length of time), and any perioperative mortality due to airway complications. None of these patients received inducation therapy. All pts received IV methylprednisolone with an initial dose of 10 mg/kg coming off the pump and then 5 mg/kg/dose q 8H x 3 doses (max 125 mg/dose). For the next 3–5 days, the IV methylprednisolone dose is 0.5 mg/kg/dose q 12H. Steroid dose is weaned by 0.1 mg/kg/day with the aim of achieving 0.5 mg/kg/day by 1 month post-transplant. During the study period
from Aug 2003 through Sept 2004, 71 patients (age 13.2⫾4.9yrs; 52 CF, 14 PH, 5 pts with non-purulent lung disease) have undergone 74 bilateral lung transplant procedures (3 redos; 51 living donor and 23 cadaveric) at our center. 1 pt, who had been on high-dose steroids for ⬎10 yrs had an air leak noted in the immediate perioperative period and went back to the OR for successful surgical repair. Thus, the incidence of airway deshiscence was only 1%. There was no prolonged air leak in any patients. There have been no deaths due to airway complications. We conclude that daily use of IV steroids during the first post-operative week does not cause significant airway complications in lung transplant recipients.
289 AUTOLOGOUS TISSUE ENGINEERED WITH MESENCHYMAL STEM CELLS FOR CARDIAC REPAIR AFTER MYOCARDIAL INFARCTION IN RATS: FEASIBILITY AND HISTOLOGICAL DATA P. Maureira,1 J. Nloga,1 Y. Grignon,2 Y. Li,1 T. Lacrouts,1 F. Groubatch,1 J.F. Stoltz,3 J.P. Villemot,1 N. Tran,1 1Laboratory of School Surgery, Faculty of Medicine-Nancy, Nancy, France; 2 Laboratory of Pathology, University Hospital Center of Nancy, Nancy, France; 3Department of Cell Therapy and Tissue Engineering, UMR-CNRS 7563, Faculty of Medicine-Nancy, Nancy, France Introduction: In chronic stage after myocardial infarction (MI) with extensive fibrous deposition and LV thinning process, in vitro engineered cardiac tissues provide new materials for in vivo cardiac surgery repair. We investigated whether the cardiac engraftment of autologous tissue engineered with bone marrow mesenchymal stem cells (BMSCs) would incorporate into the chronic ischemic myocardium and then promote angiogenesis. Methods: Artificial tissue (AT) samples were engineered by seeding rat BrdU labelled-BMSCs with 3-dimentional collagen matrix. Two weeks after tissue culture, circular ATs (1mm thick, 1mm high, 10mm diameter) were sutured into the scar areas of 1-mo coronary ligated rat hearts (n ⫽ 12). Results: One month after grafft, histological studies have shown that AT survived and completly incorporated into the damaged myocardium. Planimetry has monstrated no change in LV chamber diameter but an enhance in the LV thickness (P⬍0.05 vs MI rats, n ⫽ 12). Furthermore, immunohistochemical studies have demonstrated that angiogenesis was drammatically increased within the grafted areas and neovessels were stained positively with both BrdU and CD31. Other cell component in AT graft formed multiple cell layers with myofribroblastic phenotype. No evidence of new cardiomyocytes were detected in the grafted areas. Conclusions: We provide the first evidence for the general feasibility of BMSCs engineered tissue as material for a novel autologous tissue replacement strategy. The use of myocytes derived BMSCs as a step forward to cardiac tissue engineering might be a promising approach to reconstitute degenerated tissue.
290 IN VIVO LOCATION OF INTRAMYOCARDIAL IMPLANTED 111 IN-OXINE LABELED MESENCHYMAL STEM CELLS: ASSESSEMENT WITH DUAL ENERGY PINHOLE 99mTC-SESTAMIBI SPECT IN A RAT MODEL OF MYOCARDIAL INFARCTION N. Tran,1,2 F. Maskali,3 P. Franken,4 J. Nloga,1 T. Lahoutte,4 P. Maureira,1 Y. LI,1 P.Y. Marie,3 G. Karcher,3 J.F. Stoltz,2
The Journal of Heart and Lung Transplantation Volume 24, Number 2S
J.P. Villemot,1 1Laboratory of Surgery School, Faculty of MedicineNancy, Nancy, France; 2Department of Cell Therapy and Tissue Engineering, UMR7563 CNRS, Faculty of Medicine-Nancy, Nancy, France; 3Department of Nuclear Medicine- EA3447, CHU-Nancy, University Hospital Center of Nancy, Nancy, France; 4Department of Nuclear Medicine, AZ-VUB, Brussels, Belgium Introduction: We tested the usefulness of Pinhole 99mTc-Sestamibi gated-SPECT with dual energy recording to truly monitor 111In-oxine labeled bone marrow mesenchymal cells (BMSCs) once injected in infarct myocardium of rat. Methods: In 8 coronary ligated rats, serial pinhole 99mTc-Sestamibi gated-SPECT acquired up to three months has provided evidences of perfusion abnormalities (ranging from 10%-52% of the left ventricle). Thereafter, autologous BMSCs labeled with 111In-oxine were injected in visually located damaged areas. Three days after, cardiac pinhole 99m Tc-Sestamibi SPECT (64x64 matrix, 2.0 zoom, 360° circular orbit, 22.5 radius rotation, 64 projections and no ECG triggering) were performed one hour after the intravenous injection of 200 MBq of 99m Tc-Sestamibi with dual energy recording of activities from 99mTc (140 ⫾20% KeV) and 111In-oxine (172⫾15% and 246⫾15% photopeaks). Results: Reconstructed cardiac images have shown that 111In-oxine labelled BMSCs were located in infarct areas (4 rats), in peri-infarct areas (2 rats) and in the remote normal myocardium distant from injured tissue (2 rats). At this time, 111In-oxine signal displayed a spot in the site of injection and no evidences of redistribution of transplanted cells was seen within the heart. Conclusion: The pinhole SPECT technique with dual energy recording allows us to monitor in vivo the short-term exact location of implanted BMSCs. Such a determination might have importance for analyzing the contribution of these cells to repair damaged heart. 291 WITHDRAWN 292 INTERACTIONS BETWEEN COMPLEMENT AND COAGULATION IN MOUSE LUNG HYPERACUTE REJECTION: CHARACTERIZATION USING SOLUBLE THROMBIN INHIBITION AND APT070, A NOVEL MEMBRANE-BOUND COMPLEMENT INHIBITOR B.N. Nguyen,1 T. Zhang,1 A. Laaris,1 N. Coppard,2 B. Bradford,2 R.N. Pierson III,1 A.M. Azimzadeh 1University of Maryland, Baltimore, MD; 2Adprotech, Essex, United Kingdom Background: The mechanism of hyperacute lung rejection (HALR) is not completely understood, but appears less dependent on antibody and complement than HAR of other organs. Here we investigated the interaction between complement and thrombin activation in HALR. Methods: C3H mouse lungs were perfused with heparinized human blood treated with either: vehicle (n⫽4); APT070 (three external domains of complement inhibitor sCR1 linked to an addressin that targets binding to the cell membrane, n⫽4); Hirulog (soluble thrombin inhibitor, n⫽3); Hirulog⫹APT070 (n⫽3). Lung survival (MST) was defined by loss of volume, tracheal edema, or pulmonary vascular resistance (PVR) ⬎150. Plasma C3a was measured by ELISA, and expression of CD62P on blood platelets was quantified by flow cytometry. Results: C3a production was diminished by APT070 at 15 minutes (590⫾243 ng/ml, vs 2442⫾626 ng/ml in vehicle group; p⫽0.03) and at 60 minutes. Interestingly, Hirulog alone also significantly blocked C3a production at 15 minutes (613⫾85 ng/ml, p⫽0.05) and at 60 minutes compared to vehicle group. Whereas there was no difference in survival between APT070- and vehicle-treated groups, addition of
Abstracts
S137
Hirulog prolonged survival (79⫾6 min) compared to vehicle group (37⫾14 min) (p⫽0.06). Hirulog, but not APT070, effectively delayed PVR rise (81⫾4 mmHg-min/ml at 30 minutes vs 120⫾17 mmHgmin/ml in vehicle group (p⫽0.05). Finally, Hirulog, but not APT070, decreased platelet CD62P expression. Conclusion: APT070 is an effective complement inhibitor but alone was not sufficient to prevent PVR elevation associated with HALR. Interestingly, direct inhibition of thrombin with Hirulog not only decreased platelet activation but also decreased elaboration of complement and prolonged survival. This observation replicates previous findings in the pig-human HALR, and further supports a crucial role for coagulation dysregulation in HALR. 293 SUCCESSFUL CONTROL OF EARLY BACTERIAL AND FUNGAL INFECTIONS IN A PRECLINICAL CARDIAC XENOTRANSPLANTATION MODEL THAT ACHIEVES PROLONGED SURVIVAL S.S. Teotia,1 R.C. Walker,1 J.M. Schirmer,1 H.D. Tazelaar,1 G.W. Byrne,1 J.S. Logan,1 C.G.A. McGregor,1 1William J von Liebig Transplant Center, Mayo Clinic College of Medicine, Rochester, MN Background: We analyzed infection in a cohort of 16 consecutive experiments with the longest surviving cardiac xenografts to date. Methods: Transgenic, porcine-to-baboon, heterotopic (abdomen) cardiac xenotransplantation was performed in 16 consecutive experiments, using rapamycin, tacrolimus, corticosteroids, anti-CD20 monoclonal antibody, and TPC (an alpha-Gal-PEG polymer), as immunosuppression. Prophylactic antimicrobials included TMP/SMX, oral ganciclovir/valganciclovir, and oral itraconazole. An episode of bacterial infection was defined as a positive blood with: leukocytosis, fever ⬎ 101.5° F, and/or clinical deterioration. Results: Mean graft survival was 71⫾ 29 days; the longest was 113 days. There were 23 episodes of bacterial infection; 14 resolved with treatment. The mean time to the first episode of infection was 44⫾21 days (n⫽12). Eight of 16 deaths were due to infection: 2 bacterialonly, 3 CMV (baboon)-only, 3 both bacterial and CMV, and none fungal. Reactivation of baboon CMV was associated with low serum levels of ganciclovir. Successful treamtent of bacterial infections added 30 days to graft/animal survival (Figure 1 Curve A versus Curve B); if CMV prophylaxis could have been optimized, another 30 days of survival would have been attained (Curve B versus Curve C). Conclusion: In a cardiac xenograft model that achieved prolonged survival (⬎3 months), most episodes of bacteremia were reversible, and fungal infection was prevented—results that are similar to the early clinical experiences in human transplantation. Better prophylaxis of CMV may further increase survival.
Abstracts
The Journal of Heart and Lung Transplantation February 2005
287 RENAL BENEFIT OF RAPAMYCIN IN PEDIATRIC HEART TRANSPLANT PATIENTS I.C. Balfour, S.W. Srun, E.G. Wood, C.W. Belsha, D.L. Marshall, B.R. Ferdman, Department of Pediatrics, Saint Louis University School of Medicine, Saint Louis, MO Background: Calcineurin inhibitors (CNI) are effective in preventing rejection in recipients of solid organ transplants, but these agents are nephrotoxic. Rapamycin (RAPA) when used in conjunction with CNI, allows a lower dose of CNI to be used, potentially reducing renal damage. Pediatric heart transplant patients (Pts) were studied to determine if their renal function improved after initiating RAPA. Methods: RAPA was started in 15 pts with reduced (10) or no CNI (5). We studied renal and other parameters before and after RAPA was started. Pts were 4.1 ⫾ 5.7 yrs old (mean ⫾ 1 standard deviation) at transplant (median 0.4 yrs) and 10.3 ⫾ 4.6 yrs old when switched to RAPA (median 9.2 yrs), 10 were male. Indications for RAPA were worsening renal function (10), to improve adherence (2), change in protocol (2), post transplant lymphoproliferative disease (1). The pre and post RAPA data were compared using a paired-samples T-test. Results: At 30 days after RAPA the calculated creatinine clearance (Schwartz formula) increased from 88 ⫾ 28 ml/min/1.73M2 to 105 ⫾ 27, p .008. None of the patients had rejection after RAPA.
Pre-RAPA 30 days post RAPA p
BUN
Cr
Hb
WBC
Kⴙ
Mgⴙⴙ
27.1 ⫾ 12.4 18.6 ⫾ 11.1*
1.0 ⫾ 0.5 0.8 ⫾ 0.3**
11.5 ⫾ 1.7 12.0 ⫾ 1.3
5.9 ⫾ 2.1 7.7 ⫾ 3.5
5.2 ⫾ 0.5 4.5 ⫾ 0.6***
1.6 ⫾ 0.2 1.3 ⫾ 0.4****
*0.014
**0.019
***0.010
****0.049
Conclusion: Renal function appears to improve in the short term after starting RAPA and lowering CNI dose. RAPA may be beneficial in preserving renal function in pediatric heart transplant pts. 288 INTRAVENOUS STEROIDS DO NOT INCREASE PERIOPERATIVE AIRWAY COMPLICATION RISK IN PEDIATRIC LUNG TRANSPLANT PATIENTS J. Nigro,1 M.V. Horn,1 V.A. Starnes,1 M.L. Barr,1 M.S. Woo,1 1 Cardiothoracic Surgery, Childrens Hospital Los Angeles, Los Angeles, CA Does IV steroid use during the 1st week after lung transplant surgery increase the risk of airway complications? Some centers advocate using induction therapy and then holding steroids from Day 2 thru Day 7. However, use of induction therapy carries increased infection risk and expense. To determine if airway complications (airway dehiscence) are associated with IV steroid use in the immediate post-transplant period, we performed a retrospective review of all lung transplantations performed at our center. Heart-lung transplant recipients were excluded from analysis. Data collected: pt age, primary diagnosis, type of transplant (cadaveric or living donor), airway culture results prior to transplant, occurrence of airway complications (dehiscence, poor wound healing, prolonged air leak, etc), pre-transplant use of steroids (dose /length of time), and any perioperative mortality due to airway complications. None of these patients received inducation therapy. All pts received IV methylprednisolone with an initial dose of 10 mg/kg coming off the pump and then 5 mg/kg/dose q 8H x 3 doses (max 125 mg/dose). For the next 3–5 days, the IV methylprednisolone dose is 0.5 mg/kg/dose q 12H. Steroid dose is weaned by 0.1 mg/kg/day with the aim of achieving 0.5 mg/kg/day by 1 month post-transplant. During the study period
from Aug 2003 through Sept 2004, 71 patients (age 13.2⫾4.9yrs; 52 CF, 14 PH, 5 pts with non-purulent lung disease) have undergone 74 bilateral lung transplant procedures (3 redos; 51 living donor and 23 cadaveric) at our center. 1 pt, who had been on high-dose steroids for ⬎10 yrs had an air leak noted in the immediate perioperative period and went back to the OR for successful surgical repair. Thus, the incidence of airway deshiscence was only 1%. There was no prolonged air leak in any patients. There have been no deaths due to airway complications. We conclude that daily use of IV steroids during the first post-operative week does not cause significant airway complications in lung transplant recipients.
289 AUTOLOGOUS TISSUE ENGINEERED WITH MESENCHYMAL STEM CELLS FOR CARDIAC REPAIR AFTER MYOCARDIAL INFARCTION IN RATS: FEASIBILITY AND HISTOLOGICAL DATA P. Maureira,1 J. Nloga,1 Y. Grignon,2 Y. Li,1 T. Lacrouts,1 F. Groubatch,1 J.F. Stoltz,3 J.P. Villemot,1 N. Tran,1 1Laboratory of School Surgery, Faculty of Medicine-Nancy, Nancy, France; 2 Laboratory of Pathology, University Hospital Center of Nancy, Nancy, France; 3Department of Cell Therapy and Tissue Engineering, UMR-CNRS 7563, Faculty of Medicine-Nancy, Nancy, France Introduction: In chronic stage after myocardial infarction (MI) with extensive fibrous deposition and LV thinning process, in vitro engineered cardiac tissues provide new materials for in vivo cardiac surgery repair. We investigated whether the cardiac engraftment of autologous tissue engineered with bone marrow mesenchymal stem cells (BMSCs) would incorporate into the chronic ischemic myocardium and then promote angiogenesis. Methods: Artificial tissue (AT) samples were engineered by seeding rat BrdU labelled-BMSCs with 3-dimentional collagen matrix. Two weeks after tissue culture, circular ATs (1mm thick, 1mm high, 10mm diameter) were sutured into the scar areas of 1-mo coronary ligated rat hearts (n ⫽ 12). Results: One month after grafft, histological studies have shown that AT survived and completly incorporated into the damaged myocardium. Planimetry has monstrated no change in LV chamber diameter but an enhance in the LV thickness (P⬍0.05 vs MI rats, n ⫽ 12). Furthermore, immunohistochemical studies have demonstrated that angiogenesis was drammatically increased within the grafted areas and neovessels were stained positively with both BrdU and CD31. Other cell component in AT graft formed multiple cell layers with myofribroblastic phenotype. No evidence of new cardiomyocytes were detected in the grafted areas. Conclusions: We provide the first evidence for the general feasibility of BMSCs engineered tissue as material for a novel autologous tissue replacement strategy. The use of myocytes derived BMSCs as a step forward to cardiac tissue engineering might be a promising approach to reconstitute degenerated tissue.
290 IN VIVO LOCATION OF INTRAMYOCARDIAL IMPLANTED 111 IN-OXINE LABELED MESENCHYMAL STEM CELLS: ASSESSEMENT WITH DUAL ENERGY PINHOLE 99mTC-SESTAMIBI SPECT IN A RAT MODEL OF MYOCARDIAL INFARCTION N. Tran,1,2 F. Maskali,3 P. Franken,4 J. Nloga,1 T. Lahoutte,4 P. Maureira,1 Y. LI,1 P.Y. Marie,3 G. Karcher,3 J.F. Stoltz,2
The Journal of Heart and Lung Transplantation Volume 24, Number 2S
J.P. Villemot,1 1Laboratory of Surgery School, Faculty of MedicineNancy, Nancy, France; 2Department of Cell Therapy and Tissue Engineering, UMR7563 CNRS, Faculty of Medicine-Nancy, Nancy, France; 3Department of Nuclear Medicine- EA3447, CHU-Nancy, University Hospital Center of Nancy, Nancy, France; 4Department of Nuclear Medicine, AZ-VUB, Brussels, Belgium Introduction: We tested the usefulness of Pinhole 99mTc-Sestamibi gated-SPECT with dual energy recording to truly monitor 111In-oxine labeled bone marrow mesenchymal cells (BMSCs) once injected in infarct myocardium of rat. Methods: In 8 coronary ligated rats, serial pinhole 99mTc-Sestamibi gated-SPECT acquired up to three months has provided evidences of perfusion abnormalities (ranging from 10%-52% of the left ventricle). Thereafter, autologous BMSCs labeled with 111In-oxine were injected in visually located damaged areas. Three days after, cardiac pinhole 99m Tc-Sestamibi SPECT (64x64 matrix, 2.0 zoom, 360° circular orbit, 22.5 radius rotation, 64 projections and no ECG triggering) were performed one hour after the intravenous injection of 200 MBq of 99m Tc-Sestamibi with dual energy recording of activities from 99mTc (140 ⫾20% KeV) and 111In-oxine (172⫾15% and 246⫾15% photopeaks). Results: Reconstructed cardiac images have shown that 111In-oxine labelled BMSCs were located in infarct areas (4 rats), in peri-infarct areas (2 rats) and in the remote normal myocardium distant from injured tissue (2 rats). At this time, 111In-oxine signal displayed a spot in the site of injection and no evidences of redistribution of transplanted cells was seen within the heart. Conclusion: The pinhole SPECT technique with dual energy recording allows us to monitor in vivo the short-term exact location of implanted BMSCs. Such a determination might have importance for analyzing the contribution of these cells to repair damaged heart. 291 WITHDRAWN 292 INTERACTIONS BETWEEN COMPLEMENT AND COAGULATION IN MOUSE LUNG HYPERACUTE REJECTION: CHARACTERIZATION USING SOLUBLE THROMBIN INHIBITION AND APT070, A NOVEL MEMBRANE-BOUND COMPLEMENT INHIBITOR B.N. Nguyen,1 T. Zhang,1 A. Laaris,1 N. Coppard,2 B. Bradford,2 R.N. Pierson III,1 A.M. Azimzadeh 1University of Maryland, Baltimore, MD; 2Adprotech, Essex, United Kingdom Background: The mechanism of hyperacute lung rejection (HALR) is not completely understood, but appears less dependent on antibody and complement than HAR of other organs. Here we investigated the interaction between complement and thrombin activation in HALR. Methods: C3H mouse lungs were perfused with heparinized human blood treated with either: vehicle (n⫽4); APT070 (three external domains of complement inhibitor sCR1 linked to an addressin that targets binding to the cell membrane, n⫽4); Hirulog (soluble thrombin inhibitor, n⫽3); Hirulog⫹APT070 (n⫽3). Lung survival (MST) was defined by loss of volume, tracheal edema, or pulmonary vascular resistance (PVR) ⬎150. Plasma C3a was measured by ELISA, and expression of CD62P on blood platelets was quantified by flow cytometry. Results: C3a production was diminished by APT070 at 15 minutes (590⫾243 ng/ml, vs 2442⫾626 ng/ml in vehicle group; p⫽0.03) and at 60 minutes. Interestingly, Hirulog alone also significantly blocked C3a production at 15 minutes (613⫾85 ng/ml, p⫽0.05) and at 60 minutes compared to vehicle group. Whereas there was no difference in survival between APT070- and vehicle-treated groups, addition of
Abstracts
S137
Hirulog prolonged survival (79⫾6 min) compared to vehicle group (37⫾14 min) (p⫽0.06). Hirulog, but not APT070, effectively delayed PVR rise (81⫾4 mmHg-min/ml at 30 minutes vs 120⫾17 mmHgmin/ml in vehicle group (p⫽0.05). Finally, Hirulog, but not APT070, decreased platelet CD62P expression. Conclusion: APT070 is an effective complement inhibitor but alone was not sufficient to prevent PVR elevation associated with HALR. Interestingly, direct inhibition of thrombin with Hirulog not only decreased platelet activation but also decreased elaboration of complement and prolonged survival. This observation replicates previous findings in the pig-human HALR, and further supports a crucial role for coagulation dysregulation in HALR. 293 SUCCESSFUL CONTROL OF EARLY BACTERIAL AND FUNGAL INFECTIONS IN A PRECLINICAL CARDIAC XENOTRANSPLANTATION MODEL THAT ACHIEVES PROLONGED SURVIVAL S.S. Teotia,1 R.C. Walker,1 J.M. Schirmer,1 H.D. Tazelaar,1 G.W. Byrne,1 J.S. Logan,1 C.G.A. McGregor,1 1William J von Liebig Transplant Center, Mayo Clinic College of Medicine, Rochester, MN Background: We analyzed infection in a cohort of 16 consecutive experiments with the longest surviving cardiac xenografts to date. Methods: Transgenic, porcine-to-baboon, heterotopic (abdomen) cardiac xenotransplantation was performed in 16 consecutive experiments, using rapamycin, tacrolimus, corticosteroids, anti-CD20 monoclonal antibody, and TPC (an alpha-Gal-PEG polymer), as immunosuppression. Prophylactic antimicrobials included TMP/SMX, oral ganciclovir/valganciclovir, and oral itraconazole. An episode of bacterial infection was defined as a positive blood with: leukocytosis, fever ⬎ 101.5° F, and/or clinical deterioration. Results: Mean graft survival was 71⫾ 29 days; the longest was 113 days. There were 23 episodes of bacterial infection; 14 resolved with treatment. The mean time to the first episode of infection was 44⫾21 days (n⫽12). Eight of 16 deaths were due to infection: 2 bacterialonly, 3 CMV (baboon)-only, 3 both bacterial and CMV, and none fungal. Reactivation of baboon CMV was associated with low serum levels of ganciclovir. Successful treamtent of bacterial infections added 30 days to graft/animal survival (Figure 1 Curve A versus Curve B); if CMV prophylaxis could have been optimized, another 30 days of survival would have been attained (Curve B versus Curve C). Conclusion: In a cardiac xenograft model that achieved prolonged survival (⬎3 months), most episodes of bacteremia were reversible, and fungal infection was prevented—results that are similar to the early clinical experiences in human transplantation. Better prophylaxis of CMV may further increase survival.