Satyajit Bhattacharya

Locating the stem cell niche and tracing hepatocyte lineages in human liver.

We have used immunohistochemical and histochemical techniques to identify patches of hepatocytes deficient in the enzyme cytochrome c oxidase, a component of the electron transport chain and encoded by mitochondrial DNA (mtDNA). These patches invariably abutted the portal tracts and expanded laterally as they spread toward the hepatic veins. Here we investigate, using mtDNA mutations as a marker of clonal expansion, the clonality of these patches. Negative hepatocytes were laser‐capture microdissected and mutations identified by polymerase chain reaction sequencing of the entire mtDNA genome. Patches of cytochrome c oxidase–deficient hepatocytes were clonal, suggesting an origin from a long‐lived cell, presumably a stem cell. Immunohistochemical analysis of function and proliferation suggested that these mutations in cytochrome c oxidase‐deficient hepatocytes were nonpathogenic. Conclusion: these data show, for the first time, that clonal proliferative units exist in the human liver, an origin from a periportal niche is most likely, and that the trajectory of the units is compatible with a migration of cells from the periportal regions to the hepatic veins. (HEPATOLOGY 2009.)

A methodological approach to tracing cell lineage in human epithelial tissues.

Methods for lineage tracing of stem cell progeny in human tissues are currently not available. We describe a technique for detecting the expansion of a single cells progeny that contain clonal mitochondrial DNA (mtDNA) mutations affecting the expression of mtDNA‐encoded cytochrome c oxidase (COX). Because such mutations take up to 40 years to become phenotypically apparent, we believe these clonal patches originate in stem cells. Dual‐color enzyme histochemistry was used to identify COX‐deficient cells, and mutations were confirmed by microdissection of single cells with polymerase chain reaction sequencing of the entire mtDNA genome. These techniques have been applied to human intestine, liver, pancreas, and skin. Our results suggest that the stem cell niche is located at the base of colonic crypts and above the Paneth cell region in the small intestine, in accord with dynamic cell kinetic studies in animals. In the pancreas, exocrine tissue progenitors appeared to be located in or close to interlobular ducts, and, in the liver, we propose that stem cells are located in the periportal region. In the skin, the origin of a basal cell carcinoma appeared to be from the outer root sheath of the hair follicle. We propose that this is a general method for detecting clonal cell populations from which the location of the niche can be inferred, also affording the generation of cell fate maps, all in human tissues. In addition, the technique allows analysis of the origin of human tumors from specific tissue sites. STEM CELLS 2009;27:1410–1420

Imbalance of desmoplastic stromal cell numbers drives aggressive cancer processes

Epithelial tissues have sparse stroma, in contrast to their corresponding tumours. The effect of cancer cells on stromal cells is well recognized. Increasingly, stromal components, such as endothelial and immune cells, are considered indispensable for cancer progression. The role of desmoplastic stroma, in contrast, is poorly understood. Targeting such cellular components within the tumour is attractive. Recent evidence strongly points towards a dynamic stromal cell participation in cancer progression that impacts patient prognosis. The role of specific desmoplastic stromal cells, such as stellate cells and myofibroblasts in pancreatic, oesophageal and skin cancers, was studied in bio‐engineered, physiomimetic organotypic cultures and by regression analysis. For pancreatic cancer, the maximal effect on increasing cancer cell proliferation and invasion, as well as decreasing cancer cell apoptosis, occurs when stromal (pancreatic stellate cells) cells constitute the majority of the cellular population (maximal effect at a stromal cell proportion of 0.66–0.83), accompanied by change in expression of key molecules such as E‐cadherin and β‐catenin. Gene‐expression microarrays, across three tumour types, indicate that stromal cells consistently and significantly alter global cancer cell functions such as cell cycle, cell–cell signalling, cell movement, cell death and inflammatory response. However, these changes are mediated through cancer type‐specific alteration of expression, with very few common targets across tumour types. As highlighted by these in vitro data, the reciprocal relationship of E‐cadherin and polymeric immunoglobulin receptor (PIGR) expression in cancer cells could be shown, in vivo, to be dependent on the stromal content of human pancreatic cancer. These studies demonstrate that context‐specific cancer–stroma crosstalk requires to be precisely defined for effective therapeutic targeting. These data may be relevant to non‐malignant processes where epithelial cells interact with stromal cells, such as chronic inflammatory and fibrotic conditions. Copyright

A comparison of pancreaticoduodenectomy with extended pancreaticoduodenectomy: A meta-analysis of 1909 patients

AIM To compare outcomes between pancreaticoduodenectomy (PD) and extended pancreaticoduodenectomy (EPD) from all published comparative studies in the literature. METHODS Using meta-analytical techniques the present study compared operative details, post-operative adverse events and survival following PD and EPD. Comparative studies published between 1988 and 2005 of PD versus EPD were included. End points were classified into peri-operative details, post-operative complications including 30day mortality, and survival as measured during follow up. A random effect model was employed. RESULTS Sixteen comparative studies comprising 1909 patients (865 PD and 1044 EPD), including 3 randomized controlled trials with 454 patients (226 PD and 228 EPD) were identified. Tumour size was comparable between the groups (weighted mean difference (WMD) -0.16 cm, p=0.76). Significantly more lymph nodes were harvested from those patients undergoing EPD (WMD p=14 nodes, p< or =0.001). Operative time was longer in EPD (WMD -48.9 min, p<0.001) and there was a trend towards fewer positive resection margins (odds ratio (OR) 1.78, p=0.080). Peri-operative adverse events were similar between the groups with only delayed gastric emptying (OR 0.59, p=0.030) occurring less frequently in the PD group. Peri-operative mortality (OR 1.48, p=0.180) and long-term survival (hazard ratio 0.77, p=0.100) showed a non-significant trend favouring EPD. CONCLUSIONS EPD is associated with a greater nodal harvest and fewer positive resection margins than PD. However, the risk of delayed gastric emptying is increased and no significant survival benefit has been shown. Better designed, adequately powered studies are required to settle this question.

A comparison of pancreaticoduodenectomy with pylorus preserving pancreaticoduodenectomy: a meta-analysis of 2822 patients.

BACKGROUND The gold-standard for surgical excision of peri-ampullary tumours has not been established despite numerous studies, due to conflicting outcomes. AIM To consolidate the published evidence and compare outcomes between pancreaticoduodenectomy (PD) and pylorus preserving pancreaticoduodenectomy (PPPD) across all published comparative studies. METHODS Using meta-analytical techniques the study compared: operative details, post-operative adverse events and survival following PD and PPPD. Comparative studies published between 1986 and 2005 of PD versus PPPD were included. A random effect model was employed, with significance reported at the 5% level. RESULTS 32 studies comprising 2822 patients (1335 PD and 1487 PPPD), including 5 randomized controlled trials with 421 patients (215 PD and 206 PPPD) were included. Patients undergoing PPPD were found to have smaller tumours (weighted mean difference (WMD) -0.54 cm, p=0.030), although no significant difference in the number of patients with stage III or IV disease existed between the groups (odds ratio, OR 1.55, p=0.320). Decreased operating times (WMD -41.3 min, p=0.010) and fewer blood transfusions (WMD -0.9 units, p<0.001) were observed in the PPPD group. There was no difference in post-operative complications, including pancreatic and biliary leaks or fistulae, between the two groups. It was suggested that peri-operative mortality was decreased in the PPPD group (OR 1.7, p=0.040), and overall survival was better (hazard ratio (HR) 0.66, p=0.02), although this did not remain significant on subgroup analysis. CONCLUSIONS Both PD and PPPD had similar peri-operative adverse events, however, in overall analysis PPPD has lower mortality and improved long-term patient survival, although this was not reflected in the sub-group analysis.

Neuroendocrine tumours of the gallbladder: three cases and a review of the literature

Primary neuroendocrine tumours (NETs) of the gallbladder are rare. In the absence of any randomised controlled trials or prospective case series, we sought trends for clinical presentation and management based on 60 patients from published literature over the last 15 years, as well as three patients from our experience, and categorised them into various subgroups according to the WHO classification for NETs. Well-differentiated NETs have an indolent course and better prognosis. Poorly differentiated neuroendocrine carcinomas, which may be of large-cell or small-cell type and may coexist with other types of carcinoma, have a poor outcome. A variety of surgical and chemotherapeutic approaches have been adopted. Surgical excision appears to prolong life, with chemotherapy perhaps adding a marginal advantage.

Virtual online consultations: advantages and limitations (VOCAL) study.

Introduction Remote video consultations between clinician and patient are technically possible and increasingly acceptable. They are being introduced in some settings alongside (and occasionally replacing) face-to-face or telephone consultations. Methods To explore the advantages and limitations of video consultations, we will conduct in-depth qualitative studies of real consultations (microlevel) embedded in an organisational case study (mesolevel), taking account of national context (macrolevel). The study is based in 2 contrasting clinical settings (diabetes and cancer) in a National Health Service (NHS) acute trust in London, UK. Main data sources are: microlevel—audio, video and screen capture to produce rich multimodal data on 45 remote consultations; mesolevel—interviews, ethnographic observations and analysis of documents within the trust; macrolevel—key informant interviews of national-level stakeholders and document analysis. Data will be analysed and synthesised using a sociotechnical framework developed from structuration theory. Ethics approval City Road and Hampstead NHS Research Ethics Committee, 9 December 2014, reference 14/LO/1883. Planned outputs We plan outputs for 5 main audiences: (1) academics: research publications and conference presentations; (2) service providers: standard operating procedures, provisional operational guidance and key safety issues; (3) professional bodies and defence societies: summary of relevant findings to inform guidance to members; (4) policymakers: summary of key findings; (5) patients and carers: ‘what to expect in your virtual consultation’. Discussion The research literature on video consultations is sparse. Such consultations offer potential advantages to patients (who are spared the cost and inconvenience of travel) and the healthcare system (eg, they may be more cost-effective), but fears have been expressed that they may be clinically risky and/or less acceptable to patients or staff, and they bring significant technical, logistical and regulatory challenges. We anticipate that this study will contribute to a balanced assessment of when, how and in what circumstances this model might be introduced.

Inflammatory and Immune Responses to Surgery and Their Clinical Impact.

Objective: The aim of this study was to describe current understanding of the local and systemic immune responses to surgery and their impact on clinical outcomes, predictive biomarkers, and potential treatment strategies. Background: Patients undergoing major surgery are at risk of life-threatening inflammatory complications that include infection, the systemic inflammatory response syndrome (SIRS), or sepsis. Although improvements in surgical technique and peri-operative care have resulted in reduction in the rates of these complications, they remain high, especially in patients undergoing complex abdominal procedures. There are currently no drugs licensed specifically for the treatment of sepsis nor is it possible to identify those at highest risk, which would allow pre-emptive therapy that may improve outcomes. Conclusions: Local immune responses to surgery lead to systemic pro-inflammatory and immunosuppressive phases that are temporally related and proportionate in magnitude. Improved understanding of these mechanisms has implications for clinical study design and has led to the emergence of novel biomarkers such as Toll-like receptor expression. These can be used to stratify patient care pathways to maximize the benefit from current therapies or to select the right target at the right phase of illness for future drug development.

Impact of hospital volume on outcomes for pancreaticoduodenectomy: A single UK HPB centre experience ☆

BACKGROUND High hospital volume has a favorable impact on outcomes for complex procedures including pancreaticoduodenectomy (PD); however, the temporal relationship has not been evaluated in a single centre. AIM To evaluate the impact of UK cancer outcome guidelines (COG) on outcomes for PD in a single UK HPB specialist centre. PATIENTS AND METHODS All patients with pancreatic pathologies undergoing surgery at our institution from 1999 to 2006 were identified, of which 140 underwent PD. The annual caseload for PD and corresponding outcomes for length of hospital stay, morbidity, mortality and survival were analysed during the period around the implementation of UK COG with an increase in the surgical workload correlating with catchments population increase from 1.6 to 3.1 million. RESULTS Between January 1999 and December 2006, 140 patients underwent a PD (M:F 1.06:1; median age 64 (range 34-84) years). Median hospital stay was 16 days (range 7-318). The 30-day mortality was 2.8%, in-hospital mortality was 6.4% and morbidity was 37.1%. Pancreatic leak/fistula rate was 8.6%. Over the 7-year period, PDs per year increased 5.3 fold from 6 procedures in 1999 to 32 in 2006. Analysis of the data for 1999-2002-(pre-COG) and 2003-2006-(post-COG) showed a trend towards decrease in mortality (from 9.7% to 5.0%, p = 0.448: OR = 2.74 (95% CI, 0.58-12.88); Fishers exact test) and morbidity (from 41.6% to 35.3%; OR = 1.29 (95% CI, 0.74-3.56); p = 0.565). CONCLUSION With COG implementation within a single UK pancreatic unit, the PD volume and staffing levels increased with a trend towards decreased morbidity and mortality.

Surgery for secondary tumors of the pancreas

BACKGROUND The majority of pancreatic tumors are primary. The pancreas can however be the site of metastasis from renal cell cancer, lung, colon and breast cancers. The value of surgical treatment is unclear in such situations. The aim of this study was to evaluate the outcome of surgical therapy in patients with isolated metastases to the pancreas. METHODS All patients who underwent pancreatic surgery for malignant disease from 1999 to 2005 (n=338) at the department of hepatobiliary and pancreatic surgery, the Royal London Hospital, London, were evaluated from a retrospective pancreatic database. Five patients had metastatic pancreatic cancer. Surgical outcome and survival were examined in this subset of patients. RESULTS The primary cancer was renal cell carcinoma (n=2), breast (n=1), colon (n=1) and ovarian (n=1). The two patients with renal cell carcinoma developed pancreatic metastases years from the primary diagnosis. Both patients are alive 56 and 36 months post surgery. Two patients with breast and ovarian primary presented years after diagnosis of the primary but had advanced unresectable disease. There was one patient with colonic primary and synchronous pancreatic metastasis, and had a colectomy and Whipples operation, and is alive 64 months postoperatively. CONCLUSION The pancreas is an uncommon site for metastasis. Patients can present years after the treatment of primary. Long-term survival can be achieved with pancreatic resection in a highly selected subset of patients, and patients with primary renal cell carcinoma seem to have a favorable prognosis.