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Introducción: la hepatectomía parcial es una técnica quirúrgica que ha adquirido un gran auge en los últimos años, sus indicaciones quirúrgicas son cada vez más amplias, incluyendo el trasplante de donante vivo, principalmente en la infancia. Nuestro objetivo es estudiar los cambios morfológicos que se producen en el yeyuno proximal, porque el hígado y el intestino delgado se comportan como una unidad anatómica, funcional y metabólica. Material y métodos: se han utilizado 24 ratas de la raza Wistar divididas en 2 grupos, el grupo control y el grupo experimental (30, 90 y 180 días). Se han estudiado los cambios que se originan en el yeyuno proximal después de una resección hepática parcial del 70%, valorando 4 parámetros (grosor total de la pared, altura de la vellosidad, profundidad de la cripta y grosor de la vellosidad). Resultados: se produce una elevación significativa del grosor total de la pared del yeyuno en el grupo experimental (p < 0,001). La altura de la vellosidad se incrementa en el grupo experimental significativamente respecto al grupo control (p < 0,001). Se observa un aumento en el grosor de la vellosidad en el grupo experimental y una disminución en la profundidad de las criptas que no son estadísticamente significativos. Conclusiones: la hepatectomía parcial del 70% produce unos cambios tróficos en el yeyuno proximal, que se mantienen a corto y largo plazo, ocasionando una hipertrofia de la pared y de las vellosidades.Introduction: partial hepatectomy is being used with increasing frequency and wider surgical indications including living donor transplantation, particularly in children. Our aim was to study the morphologic changes that occur in the proximal jejunum as a result of the anatomic, functional, and metabolic unity of the liver and small intestine. Material and methods: twenty-four Wistar rats were divided into 2 groups, a control group and an experimental group (30, 90, and 180 days). Changes in the proximal jejunum after 70% partial liver resection were studied by evaluating 4 parameters (total wall width, villous height, crypt depth, and villous thickness). Results: jejunal total wall width increased significantly in the experimental group (p < 0.001). Villous height increased significantly in the experimental group as compared to the control group (p < 0.001). Villous thickness increased, and crypt depth decreased in the experimental group, but these changes were not statistically significant. Conclusions: partial hepatectomy (70%) originated trophic changes in the proximal jejunum that persisted in the short and long term, giving rise to parietal and villous hypertrophy.

Objectives: The liver has an excellent ability to regenerate, and disrupted liver regeneration after various injuries leads to an unfavorable prognosis for patients. In this study, we sought to identify novel therapeutic hallmarks that are associated with yes-associated protein 1 (YAP1)-mediated hepatocyte proliferation during the process of liver regeneration., Methods: Partial hepatectomy was conducted to induce liver regeneration in rats. Primary hepatocytes were isolated and cultured. Hepatocyte proliferation was assessed using immunohistochemistry staining, and expression of YAP1 was detected. RNA sequencing and bioinformatics analysis were used to search for potential regulators of YAP1. The association between ubiquitin-specific peptidase 1 (USP1) and YAP1 was validated using in vivo and in vitro experiments., Results: YAP1 was significantly elevated in regenerative hepatocytes, especially in the nucleus. Knockdown of YAP1 using small interfering RNA or pharmacological inhibition using verteporfin significantly attenuated the proliferation of hepatocytes. The bioinformatics analysis results revealed that USP1 was associated with YAP1-mediated hepatocyte proliferation during liver regeneration. ML-323, a specific inhibitor of USP1-USP1 associated factor 1 (UAF1), significantly decreased the expression of YAP1, Cyclin D1, and proliferating cell nuclear antigen, while these decreased expressions could be rescued by YAP1 overexpression. Furthermore, ML-323 treatment significantly inhibited liver regeneration following partial hepatectomy., Conclusions: In conclusion, we identified USP1 as a novel biomarker that is associated with YAP1-mediated hepatocyte proliferation in liver regeneration. Pharmacological inhibition of USP1 by ML-323 substantially impairs hepatocyte proliferation during liver regeneration., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2023 The Japanese Society for Regenerative Medicine. Production and hosting by Elsevier B.V.)

In solid tissues homeostasis and regeneration after injury involve a complex interplay between many different cell types. The mammalian liver harbors numerous epithelial and non-epithelial cells and little is known about the global signaling networks that govern their interactions. To better understand the hepatic cell network, we isolated and purified 10 different cell populations from normal and regenerative mouse livers. Their transcriptomes were analyzed by bulk RNA-seq and a computational platform was used to analyze the cell-cell and ligand-receptor interactions among the 10 populations. Over 50,000 potential cell-cell interactions were found in both the ground state and after partial hepatectomy. Importantly, about half of these differed between the two states, indicating massive changes in the cell network during regeneration. Our study provides the first comprehensive database of potential cell-cell interactions in mammalian liver cell homeostasis and regeneration. With the help of this prediction model, we identified and validated two previously unknown signaling interactions involved in accelerating and delaying liver regeneration. Overall, we provide a novel platform for investigating autocrine/paracrine pathways in tissue regeneration, which can be adapted to other complex multicellular systems.

Due to a combination of rapid disease progression and the lack of curative treatment options, hepatocellular carcinoma (HCC) is one of the deadliest cancers worldwide. Infiltrated, monocyte-derived, tumor-associated macrophages are known to play a role in HCC pathogenesis, but the involvement of Kupffer cells (KCs) remains elusive. Here, we used the Clec4F-diphteria toxin receptor transgenic mouse model to specifically investigate the effect of KC depletion on HCC initiation, progression and neoplastic growth following liver resection. For this purpose, several HCC mouse models with varying underlying etiologies were used and partial hepatectomy was performed. Our results show that in HCC, developed on a fibrotic or non-alcoholic steatohepatitis background, depletion of embryonic KCs at the onset of HCC induction and the subsequent replacement by monocyte-derived KCs does not affect the tumor burden, tumor microenvironment or the phenotype of isolated KCs at end-stage disease. In non-chronic liver disease-associated diethylnitrosamine-induced HCC, ablation of Clec4F + KCs did not alter tumor progression or neoplastic growth following liver resection. Our results show that temporal ablation of resident KCs does not impact HCC pathogenesis, neither in the induction phase nor in advanced disease, and indicate that bone marrow-derived KCs are able to swiftly repopulate the available KC niche and adopt their phenotype., (© 2023 UICC.)

The bilateral erector spinae plane block (ESP) has been effectively used for abdominal surgery, and the placement of catheters is known to extend the benefits of the block while allowing for the adjustment of local anesthetic doses as necessary. Since fascial plane blocks require high volumes of local anesthetic and a prolonged duration of effect, typically, long-acting local anesthetics are preferred. However, lidocaine is not commonly chosen for these types of blocks due to the large volumes required and the associated risk of local anesthetic systemic toxicity. Nonetheless, we present a case report of a patient who underwent a partial hepatectomy under general anesthesia, with perioperative placement of a bilateral ESP block. Bilateral catheters were inserted, and 1% lidocaine was selected as the local anesthetic due to resource limitations. The surgery proceeded without complications, and the patient reported effective analgesia and a high level of satisfaction. Our report suggests that the utilization of lidocaine in a continuous ESP block can be a successful alternative for partial hepatectomies., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Medeiros et al.)

Background: Extrahepatic body fat could be a relevant factor affecting liver regeneration after partial hepatectomy. The aim of this study was to evaluate the potential role of body fatty tissue in liver regeneration capacity after liver resection in a cohort of living donors., Methods: We observed liver regeneration in 120 patients: 70 living donors who underwent right hepatectomy and 50 recipients who got a right graft transplantation. Liver volumetry and body fat analysis were performed based on the computed tomography images with volumetry software. The gain of liver volume was calculated between three points in time considering the absolute and percentage values: before surgery and early (median 10 days, range 4-21 days) and late (median 27 weeks, range 18-40 weeks) after surgery. Pearson's correlation was used to examine the potential correlation between adipose tissue and liver regeneration., Results: Pearson's correlation showed a significant correlation between the subcutaneous fat mass index (sFMI) and early (r=0.173, P=0.030), as well late (r=0.395, P=0.0004) percental liver volume gain in the whole collective. Under stratification in donor's and recipient's collectives, the effect of extrahepatic adipose tissue appears in multiple regression only in the donor's collective: early (β =0.219, T =2.137, P=0.036) and late (β =0.390, T =2.552, P=0.015) percental volume gain., Conclusions: Subcutaneous adipose tissue is a positive predictive factor to estimate the goodness of liver regeneration after partial hepatectomy in normosthenic donors., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://hbsn.amegroups.com/article/view/10.21037/hbsn-22-442/coif). The authors have no conflicts of interest to declare., (2023 Hepatobiliary Surgery and Nutrition. All rights reserved.)

The liver is a complicated organ within the body that performs wide-ranging and vital functions and also has a unique regenerative capacity after hepatic tissue injury and cell loss. Liver regeneration from acute injury is always beneficial and has been extensively studied. Experimental models including partial hepatectomy (PHx) reveal that extracellular and intracellular signaling pathways can help the liver recover to its equivalent size and weight prior to an injury. In this process, mechanical cues possess immediate and drastic changes in liver regeneration after PHx and also serve as main triggering factors and significant driving forces. This review summarized the biomechanics progress in liver regeneration after PHx, mainly focusing on PHx-based hemodynamics changes in liver regeneration and the decoupling of mechanical forces in hepatic sinusoids including shear stress, mechanical stretch, blood pressure, and tissue stiffness. Also discussed were the potential mechanosensors, mechanotransductive pathways, and mechanocrine responses under varied mechanical loading in vitro . Further elucidating these mechanical concepts in liver regeneration helps establish a comprehensive understanding of the biochemical factors and mechanical cues in this process. Proper adjustment of mechanical loading within the liver might preserve and restore liver functions in clinical settings, serving as an effective therapy for liver injury and diseases., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Wu, Li, Shu, Li, Zhang, Lü and Long.)

Summary In rodents and humans, the liver can efficiently restore its mass after hepatectomy. This is largely attributed to the proliferation and cell cycle re-entry of hepatocytes. On the other hand, bone marrow cells (BMCs) migrate into the liver after resection. Here, we find that a block of BMC recruitment into the liver severely impairs its regeneration after the surgery. Mobilized hematopoietic stem and progenitor cells (HSPCs) in the resected liver can fuse with hepatocytes, and the hybrids proliferate earlier than the hepatocytes. Genetic ablation of the hybrids severely impairs hepatocyte proliferation and liver mass regeneration. Mathematical modeling reveals a key role of bone marrow (BM)-derived hybrids to drive proliferation in the regeneration process, and predicts regeneration efficiency in experimentally non-testable conditions. In conclusion, BM-derived hybrids are essential to trigger efficient liver regeneration after hepatectomy. [ABSTRACT FROM AUTHOR]

Background: Achievement of complete surgical resection plays a key role in the successful treatment of children with hepatoblastoma. The aim of this study is to assess the surgical outcomes after partial liver resections for hepatoblastoma, focusing on postoperative complications, resection margins, 30-day mortality, and long-term survival.Method: Chart reviews were carried out on all patients treated for hepatoblastoma in the Netherlands between 1990 and 2013.Results: A total of 103 patients were included, of whom 94 underwent surgery. Partial hepatectomy was performed in 76 patients and 18 patients received a liver transplant as a primary procedure. In 42 of 73 (58 %) patients, one or more complications were reported. In 3 patients, information regarding complications was not available. Hemorrhage necessitating blood transfusion occurred in 33 (45 %) patients and 9 (12 %) patients developed biliary complications, of whom 8 needed one or more additional surgical interventions. Overall, 5-year disease-specific survival was 82, 92 % in the group of patients who underwent partial hepatectomy, and 77 % in the group of patients who underwent liver transplantation.Conclusions: Partial hepatectomy after chemotherapy in children with hepatoblastoma offers good chances of survival. This type of major surgery is associated with a high rate of surgical complications (58 %), which is not detrimental to survival. [ABSTRACT FROM AUTHOR]

Chronic ethanol intake impairs liver regeneration through a system-wide alteration in the regulatory networks driving the response to injury. Our study focused on the initial phase of response to 2/3rd partial hepatectomy (PHx) to investigate how adaptation to chronic ethanol intake affects the genome-wide binding profiles of the transcription factors C/EBP-β and C/EBP-α. These factors participate in complementary and often opposing functions for maintaining cellular differentiation, regulating metabolism, and governing cell growth during liver regeneration. We analyzed ChIP-seq data with a comparative pattern count (COMPACT) analysis, which exhaustively enumerates temporal patterns of discretized binding profiles to identify dominant as well as subtle patterns that may not be apparent from conventional clustering analyses. We found that adaptation to chronic ethanol intake significantly alters the genome-wide binding profile of C/EBP-β and C/EBP-α before and following PHx. A subset of these ethanol-induced changes include C/EBP-β binding to promoters of genes involved in the profibrogenic transforming growth factor-β pathway, and both C/EBP-β and C/EBP-α binding to promoters of genes involved in the cell cycle, apoptosis, homeostasis, and metabolic processes. The shift in C/EBP binding loci, coupled with an ethanol-induced increase in C/EBP-β binding at 6 h post-resection, indicates that ethanol adaptation may change both the amount and nature of C/EBP binding postresection. Taken together, our results suggest that chronic ethanol consumption leads to a spatially and temporally reorganized activity at many genomic loci, resulting in a shift in the dynamic balance and coordination of cellular processes underlying regenerative response. [ABSTRACT FROM AUTHOR]

The objective of this study was to find out the effect of intravenous pharmacopuncture on hepatic recovery after partial hepatectomy in rats. Male Sprague–Dawley rats were randomly divided into five groups: normal group, control group, saline group, and two experimental groups. Except for those in the normal group, the rats underwent partial hepatectomy. Those in the control group did not receive any treatment. Those in the saline group received an intravenous injection with saline. Those in the two experimental groups received intravenous pharmacopuncture with SihoJigak-tang or DanchiSoyo-san extracts (10 mg/kg). Serum total bilirubin and liver regeneration rate were measured on Day 7 after partial hepatectomy. Intravenous pharmacopuncture with SihoJigak-tang significantly increased the liver regeneration rate, and intravenous pharmacopuncture with DanchiSoyo-san significantly decreased serum total billirubin after partial hepatectomy. [ABSTRACT FROM AUTHOR]

Background: Activation of the immune system in terms of subseptic conditions during liver regeneration is of paramount clinical importance. However, little is known about molecular mechanisms and their mediators that control hepatocyte proliferation. We sought to determine the functional role of immune cells, especially NKT cells, in response to partial hepatectomy (PH), and to uncover the impact of the integrin lymphocyte function-associated antigen-1 (LFA-1) on liver regeneration in a subseptic setting. Methods: Wild-type (WT) and LFA-1-/- mice underwent a 2/3 PH and low-dose lipopolysaccharid (LPS) application. Hepatocyte proliferation, immune cell infiltration, and cytokine profile in the liver parenchyma were determined. Results: Low-dose LPS application after PH results in a significant delay of liver regeneration between 48h and 72h, which is associated with a reduced number of CD3+ cells within the regenerating liver. In absence of LFA-1, an impaired regenerative capacity was observed under low-dose LPS application. Analysis of different leukocyte subpopulations showed less CD3+NK1.1+ NKT cells in the liver parenchyma of LFA-1-/- mice after PH and LPS application compared to WT controls, while CD3-NK1.1+ NK cells markedly increased. Concordantly with this observation, lower levels of NKT cell related cytokines IL-12 and IL-23 were expressed in the regenerating liver of LFA-1-/- mice, while the expression of NK cell-associated CCL5 and IL-10 was increased compared to WT mice. Conclusion: A subseptic situation negatively alters hepatocyte proliferation. Within this scenario, we suggest an important impact of NKT cells and postulate a critical function for LFA-1 during processes of liver regeneration. [ABSTRACT FROM AUTHOR]

Aim The translationally controlled tumor protein (TCTP) has been reported to promote progression of many physiological processes. However, whether TCTP is involved in liver regeneration has been rarely studied. This study aimed to investigate the potential role of serum TCTP in liver regeneration after two-thirds partial hepatectomy. Methods The synthesis rate and accumulated expression of TCTP was assessed by phosphor imaging and Western blot analysis, respectively. The mRNA expression of tctp was analyzed by quantitative real-time PCR. The effect of serum TCTP on hepatocyte proliferation was investigated by bromodeoxyuridine incorporation, liver/body weight ratio, albumin concentration, and histological examination of liver following treatment of rat with anti-TCTP antibody or prokaryotic TCTP protein before hepatectomy. The MTT assay was used to examine effect of TCTP on hepatocyte proliferation in vitro. Results The results showed that the expression of intracellular and serum TCTP protein was significantly increased in rats after two-thirds partial hepatectomy. In vivo bromodeoxyuridine labeling assay suggested that treatment with anti-TCTP antibody before hepatectomy significantly decreased hepatocyte proliferation and liver/body weight ratio. The prokaryotic TCTP had a potential promoting effect on hepatocyte proliferation both in vivo and in vitro, although prokaryotic TCTP given to rats prior to hepatectomy did not increase the proliferation ratio or liver/body weight ratio. Furthermore, anti-TCTP antibody pretreatment decreased the expression of cyclin E, cdk2, and interleukin-6 in rat liver. Conclusion These findings suggest serum TCTP is involved in rat liver regeneration through promoting hepatocyte proliferation. [ABSTRACT FROM AUTHOR]

Background The nuclear factor-erythroid 2-related factor 2 (Nrf2) -antioxidant response element (ARE) pathway is important for the regulation of antioxidative stress response and detoxification. To activate the expression of its target genes, such as heme oxygenase-1 (HO-1) and NAD(P)H dehydrogenase (quinone) 1 (NQO1), Nrf2 binds to the ARE within the promoter region of these genes. Partial hepatectomy and consecutive liver regeneration lead to oxidative stress with activation of the Nrf2-ARE pathway. The aim of this study was to investigate ARE activity in vivo during liver regeneration after partial hepatectomy. Materials and methods Transgenic ARE-luc mice were used. In these mice, the luciferase reporter gene is under the control of an ARE promoter element. Following 2/3 partial hepatectomy (PHx), mice underwent in vivo bioluminescence imaging up until the ninth postoperative day. In addition, liver tissue was analyzed by immunohistochemistry (Nrf2 and HO-1), quantitative reverse transcription-PCR (HO-1 and NQO1) and in vitro luminescence assays. Results Bioluminescence imaging revealed a significant increase in Nrf2-ARE activity after PHx. The signal maximum was recorded on the third day after PHx. Seven days postoperatively, the signal almost reached baseline levels. In immunohistochemistry, significantly more hepatocytes were positive for Nrf2 and HO-1 on the third postoperative day compared with baseline levels. The mRNA expression of HO-1 and NQO1 were significantly increased on day 3 as measured by qRT-PCR. Conclusions This study demonstrated the time-dependent activation of the Nrf2-ARE system during liver regeneration in vivo . The transgenic ARE-luc mouse provided a convenient model for studying Nrf2-mediated gene expression noninvasively and may facilitate further experiments with therapeutic modulation of the antioxidative stress response. [ABSTRACT FROM AUTHOR]

Although the recognition of pain, distress and discomfort has already been described in 1985 by Morton and Griffiths there is still very little known about the establishment of score sheets especially, regarding post-surgical pain and severity assessment for laboratory animals such as rabbits. In this paper we describe the estimation of severity and recovery status of 36 female New Zealand White rabbits (NZW) in a standardized liver resection model using two different adhesive treatments and one control group. Welfare was assessed at 3–4 consecutive days after surgery using a scoring system which included the following criteria: body weight, general state, clinical results, spontaneous behavior and clinical examination. Values could range from 0 to 20 where increasing values indicated increasing severity with a predefined humane endpoint for a score ≥20 points. Documented score points were almost exclusively a result of body weight loss, whereas clinical signs and general health status had no influence on the overall sum of points scored. Behavioral variation was solely observed postoperatively, within the first 24 h, with an average score ≤1. In contrast to the classification of a laparotomy as a moderate procedure in the EU Directive 2010/63 (annex VIII) the assessment herein presented showed a mild burden in all groups according to the scoring system used. The partial hepatectomy itself, as well as the adhesive treatment using either synthetic glue VIVO-107 or fibrin glue, were well tolerated. [ABSTRACT FROM AUTHOR]

Background: Rosemary (Rosmarinus offcinsalis L) has a liver protection function under various conditions of liver damage. Rosmarinic acid, one of the pharmacological constituents of rosemary, exhibited protective effects against organ injury, including acute liver injury.Hypothesis: We hypothesize that RA stimulates liver regeneration.Study Design: In the present study, we investigated the effects and mechanism of RA administration on liver regeneration using partial hepatectomy (PH), a well-validated liver regeneration model in mice.Methods: We use a 2/3 partial hepatectomy (PH) model to induce liver regeneration. RA was administered prior to and simultaneously with PH. The regeneration process was estimated by the index of the liver to body weight (ILBW) and the expression of proliferating cell nuclear antigen (PCNA) and liver transaminases.Results: The administration of rosmarinic acid stimulated hepatocyte proliferation based on activation of the mTOR/S6K pathway. Rosmarinic acid treatment also rescued impaired liver function due to PH.Conclusion: These data demonstrate that RA is potentially useful to promote liver regeneration. [ABSTRACT FROM AUTHOR]

Osteopontin (OPN) is a member of Th1 cytokine secreted by activated lymphocytes and macrophages. However, it deserves to be studied whether OPN could promote cell activation or proliferation, and then facilitate hepatic self-repair during liver regeneration (LR). This study is designed to further reveal the effects of OPN on LR in vivo. Firstly, quantitative reverse transcription-PCR (qRT-PCR) and western blot (WB) were utilized to validate the expression profile of endogenous OPN in rat regenerating livers after partial hepatectomy (PH). Then OPN expression vector, two shRNA expression vectors and their respective test vectors were successfully constructed. Afterwards, test vectors were administrated into mouse livers via tail vein to find the more efficient shRNA. Furthermore, OPN expression vector and the more efficient shRNA expression vector were injected into rat regenerating livers, and then the changes in liver regeneration and hepatic microstructure were respectively detected by liver regeneration rate and HE staining, while the expressions of several marker genes were detected by qRT-PCR and WB. Endogenous OPN was strikingly up-regulated in both mRNA and protein level during LR, especially at 12 and 72 h after PH. The shRNA expression vector Opn(313) was found to be more efficient than Opn(887) in silencing the expression of Opn. Then OPN expression vector and Opn(313) were injected into rat remnant livers, and it showed that OPN overexpression aggravated hepatic necrosis and leukocytes infiltration, while OPN silencing inhibited liver regeneration rate and the expressions of PCNA and CCL2, but augmented that of BAX. In conclusion, OPN might enhance inflammation and cell proliferation, attenuate cell apoptosis, and ultimately facilitate liver regeneration at the termination stage of liver regeneration. [ABSTRACT FROM AUTHOR]

Rationale and Objectives: The study aimed to validate magnetic resonance imaging (MRI)-based liver volumetry as a quantitative measure of hepatic regeneration in mice subjected to partial hepatectomy, in view of routine in vivo pharmacologic studies characterizing compounds aiming to accelerate liver regeneration.Materials and Methods: Partial hepatectomy was performed in male B6 mice (n = 47). Images were acquired in 14.5 minutes from anesthetized and spontaneously respiring animals, without any gating and without administration of contrast material. Some of the mice (n = 6) were treated with 1, 4-bis [2-(3, 5-dichloropyridyloxy)] benzene (TCPOBOP), a synthetic agonist of mouse constitutive androstane receptor, or with the corresponding vehicle (n = 6). Postmortem analyses included total liver weight and histologic Ki67 expression.Results: A highly significant correlation (R = 0.98, P = 1.5 × 10-14) was obtained between the MRI-derived liver volumes and the postmortem liver weights in hepatectomized, untreated mice. MRI reliably monitored enhanced murine liver regrowth following treatment with TCPOBOP, as confirmed by comparative hepatocyte proliferation (Ki67 expression) and liver weight analysis (R = 0.96, P = 2 × 10-6).Conclusions: MRI-based monitoring of liver regrowth in mice without the requirement of euthanizing animals at several time points has been established. In comparison to terminal procedures, the number of hepatectomized mice needed to derive a liver (re)growth curve was reduced by a factor of 6. The feasibility of using this imaging approach in pharmacologic studies in the context of liver regeneration has been demonstrated. [ABSTRACT FROM AUTHOR]

Background/Aims: Hepatic fibrosis results in defective liver regeneration following partial hepatectomy. Angiotensin converting enzyme (ACE) inhibitors can enhance liver regeneration and are also involved in the reduction of hepatic fibrosis. The present study has been conducted to evaluate the potential effect of an ACE inhibitor, lisinopril, on the morphological and biochemical aspects of fibrotic liver regeneration. Materials and Methods: Eight-week old female Sprague Dawley rats were made fibrotic by intragastric carbon tetrachloride treatment. Rats were given saline or lisinopril (1 mg/kg) orally for 1 week and were subjected to sham surgery or two-third partial hepatectomy. Liver regenerative and functional capacities were determined 48 hours post surgery. Results: Lisinopril administration did not affect the regeneration rate, proliferation cell nuclear antigen count, and hepatocellular area of fibrotic livers following partial hepatectomy. No statistically significant difference between treated and control rats regarding mitotic count, hepatocyte nuclear area, and binuclear hepatocyte frequency was observed. Serum biochemical analysis showed that lisinopril non-significantly decreased the partial hepatectomy induced elevated levels of alanine aminotransferase, aspartate transaminase, and alkaline phosphatase whereas lactate dehydrogenase and total bilirubin levels were significantly reduced. No marked reduction in hepatic collagen content and alpha smooth actin positive cells was observed by lisinopril treatment. Conclusion: ACE inhibitor lisinopril did not produce major histomorphological alterations in regenerating fibrotic liver following partial hepatectomy, however, it may improve its functional capability. [ABSTRACT FROM AUTHOR]