Score prediction of anastomotic leak in colorectal surgery: a systematic review.

OBJECTIVE: Predicting the risk of anastomotic leak (AL) is of importance when defining the optimal surgical strategy in colorectal surgery. Our objective was to perform a systematic review of existing scores in the field. METHODS: We followed the PRISMA checklist (S1 Checklist). Medline, Cochrane Central and Embase were searched for observational studies reporting on scores predicting AL after the creation of a colorectal anastomosis. Studies reporting only validation of existing scores and/or scores based on post-operative variables were excluded. PRISMA 2020 recommendations were followed. Qualitative analysis was performed. RESULTS: Eight hundred articles were identified. Seven hundred and ninety-one articles were excluded after title/abstract and full-text screening, leaving nine studies for analysis. Scores notably included the Colon Leakage Score, the modified Colon Leakage Score, the REAL score, www.anastomoticleak.com and the PROCOLE score. Four studies (44.4%) included more than 1.000 patients and one extracted data from existing studies (meta-analysis of risk factors). Scores included the following pre-operative variables: age (44.4%), sex (77.8%), ASA score (66.6%), BMI (33.3%), diabetes (22.2%), respiratory comorbidity (22.2%), cardiovascular comorbidity (11.1%), liver comorbidity (11.1%), weight loss (11.1%), smoking (33.3%), alcohol consumption (33.3%), steroid consumption (33.3%), neo-adjuvant treatment (44.9%), anticoagulation (11.1%), hematocrit concentration (22.2%), total proteins concentration (11.1%), white blood cell count (11.1%), albumin concentration (11.1%), distance from the anal verge (77.8%), number of hospital beds (11.1%), pre-operative bowel preparation (11.1%) and indication for surgery (11.1%). Scores included the following peri-operative variables: emergency surgery (22.2%), surgical approach (22.2%), duration of surgery (66.6%), blood loss/transfusion (55.6%), additional procedure (33.3%), operative complication (22.2%), wound contamination class (1.11%), mechanical anastomosis (1.11%) and experience of the surgeon (11.1%). Five studies (55.6%) reported the area under the curve (AUC) of the scores, and four (44.4%) included a validation set. CONCLUSION: Existing scores are heterogeneous in the identification of pre-operative variables allowing predicting AL. A majority of scores was established from small cohorts of patients which, considering the low incidence of AL, might lead to miss potential predictors of AL. AUC is seldom reported. We recommend that new scores to predict the risk of AL in colorectal surgery to be based on large cohorts of patients, to include a validation set and to report the AUC.

Correction: Balaphas et al. Cell Therapy for Anal Sphincter Incontinence: Where Do We Stand? Cells 2021, 10, 2086.

The authors would like to add a new reference to the section "3 [...].

Spontaneous lesser omental herniation resolved by laparoscopic surgery: case report and systematic literature review.

BACKGROUND: Despite its extremely low incidence, intra-abdominal herniation through the lesser omentum is associated with a high mortality rate and must be recognized early and treated urgently. To overcome a lack of data on the management of this condition, we collected and reviewed all the reported cases of operated lesser omental hernia and presented the case of a patient treated by laparoscopy for an isolated lesser omental hernia. METHODS: According to PRISMA guidelines and using PubMed, Cochrane Library, and Web of Science, a systematic literature review of cases of lesser omental hernia treated by surgery was performed on February 12, 2023. RESULTS: Of 482 articles, 30 were included for analysis and only 9 articles presented an isolated hernia through the lesser omentum. Among these, 4 patients were female and the median age was 38. Upper abdominal pain and vomiting were reported in 7 out of 9 patients. The small bowel was responsible for 78% (7/9) of all lesser omental herniations. All of them were treated by laparotomy. In addition, we describe the case of a 65-year-old woman without prior surgical history who was treated by laparoscopy for a spontaneous closed loop hernia through the lesser omentum without any other associated hernias. CONCLUSION: Mostly associated with prior surgery or trauma, this type of herniation could sometimes occur spontaneously without any sign of peritonitis. Due to the high mortality rate, internal abdominal hernias should always be ruled out with a CT scan in front of patients presenting with persisting acute abdominal pain and no alternative diagnosis.

Incidence of diverticulitis recurrence after sigmoid colectomy: a retrospective cohort study from a tertiary center and systematic review.

INTRODUCTION: Our aim was to determine the incidence of diverticulitis recurrence after sigmoid colectomy for diverticular disease. METHODS: Consecutive patients who benefited from sigmoid colectomy for diverticular disease from January 2007 to June 2021 were identified based on operative codes. Recurrent episodes were identified based on hospitalization codes and reviewed. Survival analysis was performed and was reported using a Kaplan-Meier curve. Follow-up was censored for last hospital visit and diverticulitis recurrence. The systematic review of the literature was performed according to the PRISMA statement. Medline, Embase, CENTRAL, and Web of Science were searched for studies reporting on the incidence of diverticulitis after sigmoid colectomy. The review was registered into PROSPERO (CRD42021237003, 25/06/2021). RESULTS: One thousand three-hundred and fifty-six patients benefited from sigmoid colectomy. Four hundred and three were excluded, leaving 953 patients for inclusion. The mean age at time of sigmoid colectomy was 64.0 + / - 14.7 years. Four hundred and fifty-eight patients (48.1%) were males. Six hundred and twenty-two sigmoid colectomies (65.3%) were performed in the elective setting and 331 (34.7%) as emergency surgery. The mean duration of follow-up was 4.8 + / - 4.1 years. During this period, 10 patients (1.1%) developed reccurent diverticulitis. Nine of these episodes were classified as Hinchey 1a, and one as Hinchey 1b. The incidence of diverticulitis recurrence (95% CI) was as follows: at 1 year: 0.37% (0.12-1.13%), at 5 years: 1.07% (0.50-2.28%), at 10 years: 2.14% (1.07-4.25%) and at 15 years: 2.14% (1.07-4.25%). Risk factors for recurrence could not be assessed by logistic regression due to the low number of incidental cases. The systematic review of the literature identified 15 observational studies reporting on the incidence of diverticulitis recurrence after sigmoid colectomy, which ranged from 0 to 15% for a follow-up period ranging between 2 months and over 10 years. CONCLUSION: The incidence of diverticulitis recurrence after sigmoid colectomy is of 2.14% at 15 years, and is mostly composed of Hinchey 1a episodes. The incidences reported in the literature are heterogeneous.

Isolation and Characterization of Stem Cells from the Anal Canal Transition Zone in Pigs.

BACKGROUND: Utilization of autologous stem cells has been proposed for the treatment of anal incontinence despite a lack of understanding of their mechanism of action and of the physiological healing process of anal sphincters after injury. AIMS: We aim to develop a technique allowing isolation and further study of local mesenchymal stem cells, directly from anal canal transition zone in pig. METHODS: Anal canal was resected "en bloc" from two young pigs and further microdissected. The anal canal transition zone was washed and digested with 0.1% type I collagenase for 45 min at 37 °C. The isolated cells were plated on dishes in mesenchymal stem cell medium and trypsinized when confluent. Cells were further used for flow cytometry analysis and differentiation assays. RESULTS: The anal canal transition zone localization was confirmed with H&E staining. Following culture, cells exhibited a typical "fibroblast-like" morphology typical of stem cells. Isolated cells were positive for CD90 and CD44 but negative for CD14, CD34, CD45, CD105, CD106, and SLA-DR. Following incubation with specific differentiation medium, isolated cells differentiated into adipocytes, osteoblasts, and chondrocytes, confirming in vitro multipotency. CONCLUSIONS: Herein, we report for the first time the presence of mesenchymal stem cells in the anal canal transition zone in pigs and the feasibility of their isolation. This preliminary study opens the path to the isolation of human anal canal transition zone mesenchymal stem cells that might be used to study sphincters healing and to treat anal incontinence.

Abdominal pain patterns during COVID-19: an observational study.

Abdominal pain and liver injury have been frequently reported during coronavirus disease-2019 (COVID-19). Our aim was to investigate characteristics of abdominal pain in COVID-19 patients and their association with disease severity and liver injury.Data of all COVID-19 patients hospitalized during the first wave in one hospital were retrieved. Patients admitted exclusively for other pathologies and/or recovered from COVID-19, as well as pregnant women were excluded. Patients whose abdominal pain was related to alternative diagnosis were also excluded.Among the 1026 included patients, 200 (19.5%) exhibited spontaneous abdominal pain and 165 (16.2%) after abdomen palpation. Spontaneous pain was most frequently localized in the epigastric (42.7%) and right upper quadrant (25.5%) regions. Tenderness in the right upper region was associated with severe COVID-19 (hospital mortality and/or admission to intensive/intermediate care unit) with an adjusted odds ratio of 2.81 (95% CI 1.27-6.21, p = 0.010). Patients with history of lower abdomen pain experimented less frequently dyspnea compared to patients with history of upper abdominal pain (25.8 versus 63.0%, p < 0.001). Baseline transaminases elevation was associated with history of pain in epigastric and right upper region and AST elevation was strongly associated with severe COVID-19 with an odds ratio of 16.03 (95% CI 1.95-131.63 p = 0.010).More than one fifth of patients admitted for COVID-19 presented abdominal pain. Those with pain located in the upper abdomen were more at risk of dyspnea, demonstrated more altered transaminases, and presented a higher risk of adverse outcomes.

Mapping of etiologies of computed tomography-proven acute colitis: a prospective cohort study.

Our objective was to describe the etiologies of acute colitis and to identify patients who require diagnostic endoscopy. Patients with symptoms of gastrointestinal infection and colonic inflammation on CT were prospectively included. Those immunosuppressed, with history of colorectal cancer or inflammatory bowel disease (IBD), were excluded. Microbiological analysis of the feces was performed using PCR assays BD-Max and FilmArray (GI panel,) and fecal cultures. Fecal calprotectin was determined. Patients with negative BD-Max underwent colonoscopy. One hundred and seventy-nine patients were included. BD-Max was positive in 93 patients (52%) and FilmArray in 108 patients (60.3%). Patients with infectious colitis (n = 103, 57.5%) were positive for Campylobacter spp. (n = 57, 55.3%), Escherichia coli spp. (n = 8, 7.8%), Clostridioides difficile (n = 23, 22.3%), Salmonella spp. (n = 9, 8.7%), viruses (n = 7, 6.8%), Shigella spp. (n = 6, 5.8%), Entamoeba histolytica (n = 2, 1.9%) and others (n = 4, 3.9%). Eighty-six patients underwent colonoscopy, which was compatible with ischemic colitis in 18 patients (10.1%) and IBD in 4 patients (2.2%). Fecal calprotectin was elevated in all patients, with a mean concentration of 1922.1 ± 2895.6 µg/g, and was the highest in patients with IBD (8511 ± 9438 µg/g, p < 0.001). After exclusion of patients with infectious etiology, a fecal calprotectin > 625 µg/g allowed identifying patients with IBD with an area under ROC curve of 85.1%. To conclude, computed tomography-proven colitis was of infectious etiology in 57.5% of patients. The main pathogens identified were Campylobacter spp. (55.3%), Clostridioides difficile (22.3%) and Salmonella spp. (8.7%). Ischemic colitis (10.1%) and IBD (2.2%) were seldom represented. No colorectal cancer was found.

Optimized Isolation and Characterization of C57BL/6 Mouse Hepatic Stellate Cells.

To obtain meaningful results of hepatic stellate cell (HSC) function, it is crucial to use highly pure HSC populations. Our aim was to optimize HSC isolation from mice livers without exploiting the characteristically transient vitamin A autofluorescence of HSC. HSCs were isolated from C57BL/6 mice using a two-step collagenase digestion and Nycodenz gradient separation followed by CD11b-negative sorting step in order to remove contaminating macrophages and dendritic cells. Isolated cells were analyzed for yield, viability, purity, and potential new markers using immunofluorescence and flow cytometry. We obtained a yield of 350,595 ± 100,773 HSC per mouse liver and a viability of isolated cells of 92.4 ± 3.1%. We observed a low macrophage/dendritic cell contamination of 1.22 ± 0.54%. Using flow cytometry, we demonstrated that CD38 was expressed at the surface of HSC subpopulations and that all expressed intracellular markers specific for HSC in the liver. This isolation method, avoiding fluorescent activated cell sorting (FACS), allowed isolation of HSCs with high purity. Further, flow cytometry analysis suggests that CD38 may be a reliable marker of HSCs and may include subpopulations of HSCs without retinoid droplets.

Cell Therapy for Anal Sphincter Incontinence: Where Do We Stand?

Anal sphincter incontinence is a chronic disease, which dramatically impairs quality of life and induces high costs for the society. Surgery, considered as the best curative option, shows a disappointing success rate. Stem/progenitor cell therapy is pledging, for anal sphincter incontinence, a substitute to surgery with higher efficacy. However, the published literature is disparate. Our aim was to perform a review on the development of cell therapy for anal sphincter incontinence with critical analyses of its pitfalls. Animal models for anal sphincter incontinence were varied and tried to reproduce distinct clinical situations (acute injury or healed injury with or without surgical reconstruction) but were limited by anatomical considerations. Cell preparations used for treatment, originated, in order of frequency, from skeletal muscle, bone marrow or fat tissue. The characterization of these preparations was often incomplete and stemness not always addressed. Despite a lack of understanding of sphincter healing processes and the exact mechanism of action of cell preparations, this treatment was evaluated in 83 incontinent patients, reporting encouraging results. However, further development is necessary to establish the correct indications, to determine the most-suited cell type, to standardize the cell preparation method and to validate the route and number of cell delivery.

Sacro-coxxygial hygiene, a key factor in the outcome of pilonidal sinus surgical treatment?

BACKGROUND: Surgical wound infection contributes to prolonged recovery time after pilonidal sinus excision. As a standard procedure after surgery, we recommend our patients to perform water irrigations in the intergluteal cleft 4 to 6 times a day during the post-operative period. Our hypothesis is that this should reduce healing time and complication rates. The aim of this study was to measure the importance of sacro coccygeal hygiene in the management of pilonidal sinus disease. METHODS: We retrospectively collected data after surgical management of pilonidal sinus (sinusectomy procedures) in our division over a 10-year period. Patients were divided into three groups according to their local hygiene during postoperative follow-up and scored one (G1: good hygiene) to three (G3: poor hygiene). Primary outcome was complication rates. Secondary endpoints were, healing time, follow-up, time off work, and recurrence rate. RESULTS: In G1 (N = 112), complication rate was 3.6%. In G2 (N = 109), it was 5.5%, whereas in G3 (N = 71), it reached 7.03%. However, there were no statistically significant differences between hygiene groups regarding complication rates in both univariate and multivariable analysis. Regarding secondary outcomes, there were significant differences between hygiene groups concerning median follow-up (p = 0.0001) and median time off work (p = 0.0127). CONCLUSION: Good hygiene of wound is essential for optimal, rapid healing without complications. The importance of this report is to show that thanks to our hygiene follow-up strategy with frequent perineal irrigations and regular follow-up checks, patients with at a first glance "unclean local conditions", reached similar complications, median healing time and recurrences rates to patients with medium and good wound hygiene level.

Adherence to, and patient convenience of, prolonged-release tacrolimus in stable kidney and liver transplant recipients after conversion from immediate-release tacrolimus in routine clinical practice in Switzerland.

AIMS OF THE STUDY: Non-adherence to immunosuppressive therapy in patients following solid organ transplantation is associated with an increased risk of transplant rejection and graft loss. A high pill burden can adversely affect patients’ implementation of their treatment regimens and may lead to omitting doses of medication. The aim of this study was to investigate medication implementation adherence in liver and kidney transplant recipients converted from twice-daily, immediate-release tacrolimus to once-daily, prolonged-release tacrolimus. METHODS: This multicentre, non-interventional, observational, 12-month study evaluated implementation adherence in routine practice at five hospitals in Switzerland. Patients attended four clinical visits: at baseline (pre-conversion), and then at week 2, month 6 and month 12 post-conversion. Implementation was defined as consistently taking medication at the correct time and at the correct dose in order to achieve target tacrolimus trough levels. Implementation adherence was evaluated in three ways: using the Basel Assessment of Adherence to Immunosuppressive Medications Scale (BAASIS) interview questionnaire (at baseline and month 12), investigator-rated patient adherence (recorded at all visits), and tacrolimus trough levels (assessed throughout the study; sub-therapeutic levels were predefined by the investigator on an individual patient basis, over-therapeutic levels were defined as tacrolimus trough levels >15 ng/ml). The primary composite endpoint was non-adherence according to the BAASIS at month 12, any post-conversion investigator adherence rating of “poor”, or sub-therapeutic or over-therapeutic tacrolimus trough levels at month 6 or 12. Secondary endpoints included: individual components of the composite non-adherence primary endpoint, tacrolimus pill burden, patient satisfaction, and adverse drug reactions. RESULTS: Seventy-five patients received prolonged-release tacrolimus; 68 patients (46 kidney and 22 liver transplant recipients) completed the study. Of these 68 patients, 24 had missing data for at least one component of the primary endpoint; therefore, data for the primary composite endpoint were evaluable for 44 patients. Most (81.8%; 36/44) patients were non-adherent for the composite endpoint. Sub-therapeutic tacrolimus trough levels outside of the predefined therapeutic range were the largest contributor to the composite endpoint, and were detected in 62.0% (31/50) of patients. Overall non-adherence according to the BAASIS was similar pre-conversion (30.7%) and at 12 months post-conversion (28.3%). Investigators rated adherence as “poor” for two patients. Prolonged-release tacrolimus decreased tacrolimus pill burden in 66.7% of patients. All patients were very satisfied / satisfied with prolonged-release tacrolimus; 75.0% found it easier to remember to take prolonged-release versus immediate-release tacrolimus. Twenty percent of patients reported adverse drug reactions, with infections being the most frequently reported (9.3%). CONCLUSION: Overall, 1-year non-adherence rates were similar following conversion from immediate-release to prolonged-release tacrolimus; however, prolonged-release tacrolimus intake was more convenient. No new safety signals were detected.

Multipotent mesenchymal stromal cells derived from porcine exocrine pancreas improve insulin secretion from juvenile porcine islet cell clusters.

Neonatal and juvenile porcine islet cell clusters (ICC) present an unlimited source for islet xenotransplantation to treat type 1 diabetes patients. We isolated ICC from pancreata of 14 days old juvenile piglets and characterized their maturation by immunofluorescence and insulin secretion assays. Multipotent mesenchymal stromal cells derived from exocrine tissue of same pancreata (pMSC) were characterized for their differentiation potential and ability to sustain ICC insulin secretion in vitro and in vivo. Isolation of ICC resulted in 142 ± 50 × 103 IEQ per pancreas. Immunofluorescence staining revealed increasing presence of insulin-positive beta cells between day 9 and 21 in culture and insulin content per 500IEC of ICC increased progressively over time from 1178.4 ± 450 µg/L to 4479.7 ± 1954.2 µg/L from day 7 to 14, P < .001. Highest glucose-induced insulin secretion by ICC was obtained at day 7 of culture and reached a fold increase of 2.9 ± 0.4 compared to basal. Expansion of adherent cells from the pig exocrine tissue resulted in a homogenous CD90+ , CD34- , and CD45- fibroblast-like cell population and differentiation into adipocytes and chondrocytes demonstrated their multipotency. Insulin release from ICC was increased in the presence of pMSC and dependent on cell-cell contact (glucose-induced fold increase: ICC alone: 1.6 ± 0.2; ICC + pMSC + contact: 3.2 ± 0.5, P = .0057; ICC + pMSC no-contact: 1.9 ± 0.3; theophylline stimulation: alone: 5.4 ± 0.7; pMSC + contact: 8.4 ± 0.9, P = .013; pMSC no-contact: 5.2 ± 0.7). After transplantation of encapsulated ICC using Ca2+ -alginate (alg) microcapsules into streptozotocin-induced diabetic and immunocompetent mice, transient normalization of glycemia was obtained up to day 7 post-transplant, whereas ICC co-encapsulated with pMSC did not improve glycemia and showed increased pericapsular fibrosis. We conclude that pMSC derived from juvenile porcine exocrine pancreas improves insulin secretion of ICC by direct cell-cell contact. For transplantation purposes, the use of pMSC to support beta-cell function will depend on the development of new anti-fibrotic polymers and/or on genetically modified pigs with lower immunogenicity.

Prevalence of Metastatic Lateral Lymph Nodes in Asian Patients with Lateral Lymph Node Dissection for Rectal Cancer: A Meta-analysis.

IMPORTANCE: Rectal cancers occupy the eighth position worldwide for new cases and deaths for both men and women. These cancers have a high tendency to form metastases in the mesorectum but also in the lateral lymph nodes. The therapeutic approach for the involved lateral lymph nodes remains controversial. OBJECTIVE: We performed a systematic review and meta-analysis to assess the prevalence of metastatic lateral lymph nodes in patients with lateral lymph node dissection (LLND) for rectal cancer, which seems to be a fundamental and necessary criterion to discuss any possible indications for LLND. METHODS: Data sources-study selection-data extraction and synthesis-main outcome and measures. We searched MEDLINE, EMBASE and COCHRANE from November 1, 2018, to November 19, 2018, for studies reporting the presence of metastatic lateral lymph nodes (iliac, obturator and middle sacral nodes) among patients undergoing rectal surgery with LLND. Pooled prevalence values were obtained by random effects models, and the robustness was tested by leave-one-out sensitivity analyses. Heterogeneity was assessed using the Q-test, quantified based on the I2 value and explored by subgroup analyses. RESULTS: Our final analysis included 31 studies from Asian countries, comprising 7599 patients. The pooled prevalence of metastatic lateral lymph nodes was 17.3% (95% CI: 14.6-20.5). The inter-study variability (heterogeneity) was high (I2 = 89%). The pooled prevalence was, however, robust and varied between 16.6% and 17.9% according to leave-one-out sensitivity analysis. The pooled prevalence of metastatic lymph nodes was not significantly different when pooling only studies including patients who received neoadjuvant treatment or those without neoadjuvant treatment (p = 0.44). Meta-regression showed that the pooled prevalence was associated with the sample size of studies (p < 0.05), as the prevalence decreased when the sample size increased. CONCLUSION: The pooled prevalence of metastatic lateral lymph nodes was 17.3% among patients who underwent rectal surgery with LLND in Asian countries. Further studies are necessary to determine whether this finding could impact the therapeutic strategy (total mesorectal excision with LLND versus total mesorectal excision with neoadjuvant radiochemotherapy).

Preoperative platelet count does not predict the occurrence of post-hepatectomy liver failure after partial hepatectomy in a retrospective monocentric cohort study.

ABSTRACT: In humans, thrombocytopenic patients have increased incidence of post-hepatectomy liver failure (PHLF), but existing evidence is heterogeneous. Our objective was to determine if preoperative platelet count or antiplatelet drugs were associated with PHLF.Patients who underwent hepatic resection in the University Hospitals of Geneva, Switzerland, from 01.12.2009 to 18.12.2018 were identified. Platelet count at day 0, postoperative days (POD) 1, 3, and 5 were retrieved. Occurrence of PHLF according to the ISGLS definition was determined. Logistic regression was performed to determine if platelet count or antiplatelet drug were predictors for PHLF.Five hundred ninety seven patients were included. Eighty patients (17.8%) had a preoperative platelet count <150 (G/l) and 24 patients (5.3%) had a platelet count <100 (G/l). Thirty five patients (5.9%) were under antiplatelet drug. Platelet count significantly decreased at POD 1 and POD 3 when compared to preoperative platelet count (182 ±â€Š71.61 (G/l) vs 212 ±â€Š85.26 (G/l), P < .0001; 162 ±â€Š68.5 (G/l) vs 212 ±â€Š85.26 (G/l), P < .0001). At POD 5, post-operative platelet count did not significantly differ from its preoperative value. Forty three patients (11.2%) suffered from PHLF. Their platelet count was not significantly different than patients without PHLF (211 ±â€Š89.7 (G/l) vs 211 ±â€Š83.5 (G/l), P = .671). One patient with PHLF had a platelet count <100 (G/l) and 5 had a count <150 (G/l). Univariate logistic regression did not identify preoperative thrombocytopenia (<100 (G/l) or <150 (G/l)), postoperative thrombocytopenia, or the presence of antiagregant drug, as predictors of PHLF. We did not identify preoperative or postoperative thrombocytopenia as predictor of PHLF in a cohort of 597 patients.

Platelet Interactions with Liver Sinusoidal Endothelial Cells and Hepatic Stellate Cells Lead to Hepatocyte Proliferation.

(1) Background: Platelets were postulated to constitute the trigger of liver regeneration. The aim of this study was to dissect the cellular interactions between the various liver cells involved in liver regeneration and to clarify the role of platelets. (2) Methods: Primary mouse liver sinusoidal endothelial cells (LSECs) were co-incubated with increasing numbers of resting platelets, activated platelets, or platelet releasates. Alterations in the secretion of growth factors were measured. The active fractions of platelet releasates were characterized and their effects on hepatocyte proliferation assessed. Finally, conditioned media of LSECs exposed to platelets were added to primary hepatic stellate cells (HSCs). Secretion of hepatocyte growth factor (HGF) and hepatocyte proliferation were measured. After partial hepatectomy in mice, platelet and liver sinusoidal endothelial cell (LSEC) interactions were analyzed in vivo by confocal microscopy, and interleukin-6 (IL-6) and HGF levels were determined. (3) Results: Co-incubation of increasing numbers of platelets with LSECs resulted in enhanced IL-6 secretion by LSECs. The effect was mediated by the platelet releasate, notably a thermolabile soluble factor with a molecular weight over 100 kDa. The conditioned medium of LSECs exposed to platelets did not increase proliferation of primary hepatocytes when compared to LSECs alone but stimulated hepatocyte growth factor (HGF) secretion by HSCs, which led to hepatocyte proliferation. Following partial hepatectomy, in vivo adhesion of platelets to LSECs was significantly increased when compared to sham-operated mice. Clopidogrel inhibited HGF secretion after partial hepatectomy. (4) Conclusion: Our findings indicate that platelets interact with LSECs after partial hepatectomy and activate them to release a large molecule of protein nature, which constitutes the initial trigger for liver regeneration.

Platelet Transforming Growth Factor-ß1 Induces Liver Sinusoidal Endothelial Cells to Secrete Interleukin-6.

The roles and interactions of platelets and liver sinusoidal endothelial cells in liver regeneration are unclear, and the trigger that initiates hepatocyte proliferation is unknown. We aimed to identify the key factors released by activated platelets that induce liver sinusoidal endothelial cells to produce interleukin-6 (IL-6), a cytokine implicated in the early phase of liver regeneration. We characterized the releasate of activated platelets inducing the in vitro production of IL-6 by mouse liver sinusoidal endothelial cells and observed that the stimulating factor was a thermolabile protein. Following gel filtration, a single fraction of activated platelet releasate induced a maximal IL-6 secretion by liver sinusoidal endothelial cells (90.2 ± 13.9 versus control with buffer, 9.0 ± 0.8 pg/mL, p < 0.05). Mass spectroscopy analysis of this fraction, followed by in silico processing, resulted in a reduced list of 18 candidates. Several proteins from the list were tested, and only recombinant transforming growth factor ß1 (TGF-ß1) resulted in an increased IL-6 production up to 242.7 ± 30.5 pg/mL, which was comparable to non-fractionated platelet releasate effect. Using neutralizing anti-TGF-ß1 antibody or a TGF-ß1 receptor inhibitor, IL-6 production by liver sinusoidal endothelial cells was dramatically reduced. These results support a role of platelet TGF-ß1 ß1 in the priming phase of liver regeneration.