Introduction and Aim: Liver surgery has had an exponential development making possible the use of partial liver grafts for living donor liver transplantation (LDLT). Nonetheless, LDLT indication still depends on the graft size used for the recipient, due to the development of “small for size syndrome” (SFSS) which can be better understood through the study of hepatocellular regeneration.
The aim of this study is to analyze the liver regeneration rate (LRR, grams/day) of a healthy human liver after a major liver resection such as donation of the right hepatic lobe (RHL). We have also evaluated the LRR in the recipients of this RHL and the different factors that can affect it.
Materials and Methods: In between January 2005 to December 2015 fifty LDLT were performed in our institution, 46 donors with their respective recipients were included being the ones de RHL was used (92%). A MRI was performed during follow up at the first, third and twelve months to all donors and recipients. With this MRI, the LRR was calculated within 3 periods of time (1 month, 1-3m and 12m after donation).
Results and Discusion: The median age of the donors and recipients was 35 (r=20-46) and 57 years old (r=49-66) respectively. Fifty two percent of the donors and 84.8% of the recipients were male. Intraoperative baseline biopsy of the donor was normal in almost all cases except 7 (15%) in which we found mild steatosis (<10%). Liver transplant indication was due to end stage liver disease in 20 patients (9 alcohol related, 28 with HCV infection and 9 of other causes) and the other 26 recipients the indication was due to HCC.
The liver remnant volume in the donors was approximately 36.5% (r=30.5-45.2) of the total liver volume (1588g, r=1065-2079). The body to graft weigh ratio in the recipient had a median of 1.2 (r= 0.7-2.0). The median of the LRR in donors was of 14.5 g/d the first month, 0.47 g/d between 1-3m and of 0.49 g/d between 3-12m.  The liver volume at the end of follow up (1 year) was 1196 g (r=864-2229).
In the recipients, the LRR for the same periods of time was 13.42 g/d, 2.74 g/d and-0.26 g/d respectively and the graft volume at the end was 1503 g (r=931-2042). Interestingly the LRR in patients with HCV infection was diminished with statistical difference in the first month and in the 3-12m period after transplantation (22,19 vs 13,4 y 1,23 vs 0,14, p=0.044 y p=0.035 respectively).
Conclusions: We have confirmed how liver regeneration is an acute process that mainly develops in the first month after liver resection in a healthy liver when leaving and adequate liver remnant. This LR is similar in the context of LDLT when the graft has a correct volume, even though this regeneration can be affected by HCV re-infection.