Influence of mycophenolic acid and FK-506 on human platelet activation in vitro

The effect of mycophenolate mofetil on platelet function

: Mycophenolate mofetil (MMF) raises platelet counts in patients with primary immune thrombocytopenia. However, studies indicate that MMF inhibits collagen-induced platelet aggregation, potentially increasing bleeding risk following MMF therapy. The study evaluates the in-vitro effect of MMF on platelet function. Blood samples (n = 6) from healthy donors were incubated with vehicle, MMF or mycophenolic acid (MPA) at clinically relevant concentrations. Platelet aggregation was measured with flow cytometry and 96-well light transmission aggregometry (LTA). Using flow cytometry, we measured the expression of platelet CD49b, CD42b, CD42a, CD61 and CD41. Platelet activation was measured as the expression of P-selectin and the active form of the GPIIb/IIIa receptor following agonist stimulation. Agonists were: ADP, thrombin receptor-activating peptide, collagen, collagen-related peptide and U46619. The Platelet Function Analyzer-200 was used to measure global platelet function. MMF and MPA did not change platelet aggregation regardless of the agonist used. An exception was a significant, but minor decrease in collagen-induced platelet aggregation in samples with MMF (6 ± 3%, P = 0.02) and MPA (8 ± 4%, P = 0.01) compared with vehicle (22 ± 11%). However, this was not observed using the lesser sensitive LTA method. Compared with vehicle, MPA led to a significantly lower relative disposition of the surface collagen-receptor GPVI (7.8 ± 1.8 versus 8.8 ± 2.1 mean fluorescence intensity, P < 0.001). In all other platelet-related tests, neither MMF nor MPA showed any effect. In conclusion, MMF and MPA only had a minor effect on collagen-induced platelet aggregation, with MPA reducing the relative disposition of surface GPVI receptors.

Postoperative Complications of Plastic and Reconstructive Surgery in Solid Organ Transplant Recipients

INTRODUCTION

As the number of organ transplants and the survival rate increase, solid organ transplant patients will need more plastic and reconstructive surgery. However, such patients take immunosuppressants, including prednisone, which makes wound healing slower and plastic surgeons more hesitate to operate. In this study, we examined postoperative complications of organ transplant patients who have undergone plastic and reconstructive surgery.

MATERIALS & METHODS

Between 2002 and 2018, the total number of patients who visited our clinic after receiving organ transplants was 77. Retrospective reviews were performed on 35 patients, excluding those who received conservative treatment. Demographics, underlying diseases, causes of organ transplantation, immunosuppressive regimen, types of procedures, and postoperative complications were analyzed.

RESULTS

A total of 35 patients received 42 procedures. Eleven patients had undergone kidney transplantation, and 24 had undergone liver transplantation. The type of procedures were local flap (23.8%), primary closure (23.8%), skin graft (11.9%), and free flap (2.4%). There were 2 cases of aesthetic surgery. Among all the cases, complications occurred in 8 procedures (19%). Hematoma was the most common complication, followed by skin necrosis. All except 3 patients were completely healed within 6 weeks.

DISCUSSION

This study showed that hematoma was the most frequently occurring complication. In a few cases, wound healing was delayed. So, bleeding control was very important to prevent the development of hematoma. And organ transplants may not be a problem for plastic and reconstructive surgery.

Association between endothelial and platelet function markers and adiponectin in renal transplanted recipients on cyclosporine and tacrolimus immunosuppression based therapy

AIM

Coagulation abnormalities, endothelial dysfunction and arteriosclerosis play a key role in cardiovascular disease state observed in transplanted patients. Plasma adiponectin levels are lower following kidney transplantation. However, there is still a debate about this topic in the literature. This study evaluated, adiponectin levels associated with markers of endothelial dysfunction and platelet function in renal transplant patients.

METHODS

Sixty-six renal transplant patients were studied. Patients were grouped according to immunosuppression regimen. Group 1 (n = 36) were treated with cyclosporine A based regimes and group 2 (n = 30) were treated with tacrolimus based regimes. Plasma adiponectin, asymmetric dimethyl arginine (ADMA), sP-selectin levels and platelet aggregation tests were studied and were compared with those in control group (n = 15, group 3).

RESULTS

Adiponectin, sP-selectin and ADMA levels were higher in group 1 and statistically significant differences were observed compared with those of group 2 and group 3, respectively (P < 0.001, P < 0.05, P < 0.05). Platelet aggregation values induced by agonists were lower in group 1 than group 2 and group 3, but the difference did not reach statistical significance (P > 0.05).

CONCLUSION

Adiponectin levels are elevated in line with ADMA and sP-selectin levels. Since CsA induces higher adiponectin levels, platelet activation and endothelial dysfunction. These changes may be responsible for the increased risk of post-transplant cardiovascular events in renal transplant patients.

Effects of immunosuppressive drugs on platelet aggregation and soluble P-selectin levels in renal transplant patients

BACKGROUND/AIM

Post-transplant cardiovascular events are associated with increased morbidity and mortality after renal transplantation. Though renal transplantation eliminates cardiovascular disease risk factors by restoring renal function, it introduces new cardiovascular risks derived partly from immunosuppressive medications. In this study, to assess the effects of various immunosuppressive drugs on platelet function of renal transplant patients, we measured soluble P selectin levels (sP-selectin) and performed platelet aggregation studies in patients who have undergone renal transplantation.

METHODS

sP-selectin levels and platelet aggregation induced by 5 microM adenosine diphosphate (ADP), 5 microM epinephrine, 1.25 mg/mL ristocetin, and 2 microg/mL collagen were studied by whole blood platelet lumi-aggregometer in 40 renal transplant patients. Patients in group 1 (n = 24) were treated with cyclosporine/mycophenolate mofetil/methylprednisolone, and group 2 (n = 16) were treated with tacrolimus/mycophenolate mofetil/methylprednisolone. Effects were compared with those in control groups of hypertensive subjects and healthy subjects.

RESULTS

Platelet aggregation values induced by ADP, epinephrine, ristocetin, and collagen were lower in cyclosporine-treated patients than tacrolimus-treated patients, hypertensive subjects, and healthy subjects, though the difference was not statistically significant (p > 0.05). sP-selectin levels were appreciably higher in cyclosporine-treated patients, and statistically significant differences were observed compared with those of tacrolimus-treated patients (p < 0.05), hypertensive subjects (p < 0.01), and healthy subjects (p < 0.05).

CONCLUSION

We conclude that cyclosporine-treated renal transplant patients show enhanced platelet activation in which anti-platelet therapy should be considered, in addition to management of other conventional cardiovascular risk factors, to decrease the cardiovascular morbidity and mortality in this high risk population.