Challenges of adult living-donor liver transplantation

Functional Immune Anatomy of the Liver-As an Allograft

The liver is an immunoregulatory organ in which a tolerogenic microenvironment mitigates the relative "strength" of local immune responses. Paradoxically, necro-inflammatory diseases create the need for most liver transplants. Treatment of hepatitis B virus, hepatitis C virus, and acute T cell-mediated rejection have redirected focus on long-term allograft structural integrity. Understanding of insults should enable decades of morbidity-free survival after liver replacement because of these tolerogenic properties. Studies of long-term survivors show low-grade chronic inflammatory, fibrotic, and microvascular lesions, likely related to some combination of environment insults (i.e. abnormal physiology), donor-specific antibodies, and T cell-mediated immunity. The resultant conundrum is familiar in transplantation: adequate immunosuppression produces chronic toxicities, while lightened immunosuppression leads to sensitization, immunological injury, and structural deterioration. The "balance" is more favorable for liver than other solid organ allografts. This occurs because of unique hepatic immune physiology and provides unintended benefits for allografts by modulating various afferent and efferent limbs of allogenic immune responses. This review is intended to provide a better understanding of liver immune microanatomy and physiology and thereby (a) the potential structural consequences of low-level, including allo-antibody-mediated injury; and (b) how liver allografts modulate immune reactions. Special attention is given to the microvasculature and hepatic mononuclear phagocytic system.

Quality of life for donors after living donor liver transplantation: a review of the literature

Living donor liver transplantation (LDLT) decreases the shortage of liver grafts for patients in need of a liver transplant, but it involves 2 patients: a recipient and a living donor. Despite the magnitude of the procedure for LDLT donors, only a few studies have investigated the effect of LDLT on the quality of life (QOL) of donors. We performed a systematic search of the MEDLINE database to identify peer-reviewed articles assessing QOL in adults after LDLT donation. Nineteen studies describing 768 unique donors met our inclusion criteria for this review. The median number of donors enrolled in each study was 30 (range = 10-143), and the median follow-up period was 10.4 months (range = 3-51.3 months). Before donation, donor QOL was significantly better than that in control adult populations across all measured QOL domains. Within the first 3 months after donation, the physical domains of QOL were significantly worse than the predonation levels, but they returned to baseline levels within 6 months for the majority of patients (80%-93%). Mental domains of QOL remained unchanged throughout the donation process. Common donor concerns after LDLT included bloating, loss of muscle tone, poor body image, and fatigue. In conclusion, according to our review of the existing literature, most LDLT donors return to their baseline QOL within 6 months. However, there is a lack of long-term data on donor QOL after LDLT, and few standardized assessments include measures of common patient concerns. Additional studies are necessary to develop a comprehensive risk profile for LDLT that includes a rigorous assessment of donor QOL.

Nitric oxide reduces organ injury and enhances regeneration of reduced-size livers by increasing hepatic arterial flow

Background

Reduced-size livers suffer from portal hyperperfusion, diminished arterial blood flow and the risk of postoperative liver injury. The aim of this experimental study was to unravel the role of nitric oxide in this setting.

Methods

Rats underwent 85 per cent partial hepatectomy and either substitution of nitric oxide with molsidomine or inhibition of nitric oxide synthase (NOS) with NG-nitro-l-arginine methyl ester. Untreated hepatectomized animals served as controls and unresected animals as the sham group.

Results

Ultrasonic flowmetry following partial hepatectomy revealed a marked increase in portal venous inflow with a concomitant decrease in hepatic arterial inflow. Nitric oxide substitution counteracted the decline in hepatic arterial inflow and caused a significantly greater increase in cell proliferation after partial hepatectomy compared with control or NOS-inhibited animals. Hepatectomized animals further profited from nitric oxide substitution, as indicated by reduced aminotransferase release and improved liver function.

Conclusion

Nitric oxide improves the postoperative course of rats with reduced-size livers by modulating hepatic macrohaemodynamics and mediating regeneration and cytoprotection, but not by reducing hepatic hyperperfusion and the accompanying sinusoidal shear stress.

Strategies for improving the outcomes of small-for-size grafts in adult-to-adult living-donor liver transplantation

Living-donor liver transplantation (LDLT) has been refined and accepted as a valuable treatment for patients with end-stage liver disease in order to overcome the shortage of organs and mortality on the waiting list. However, graft size problems, especially small-for-size (SFS) grafts, remain the greatest limiting factor for the expansion of LDLT, especially in adult-to-adult transplantation. Various attempts have been made to overcome the problems regarding SFS grafts, such as increasing the graft liver volume and/or controlling excessive portal inflow to a small graft, with considerable positive outcomes. Recent innovations in basic studies have also contributed to the treatment of SFS syndrome. Herein, we review the literature and assess our current knowledge of the pathogenesis and treatment strategies for the use of SFS grafts in adult-to-adult LDLT.