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Fluorescent imaging is an emerging technological tool that can guide surgeons during surgery by highlighting anatomical structures and pathology, and help with intraoperative decision making. A comprehensive review of published literature was performed using the search terms “fluorescence”, “imaging” and “colorectal surgery” in PubMed. Only clinical trials that were published in English were included in this review. Ex vivo and animal studies were excluded. This review demonstrates the use of fluorescence imaging in colorectal surgery in four areas: (1) assessment of tissue perfusion and vasculature; (2) assessment of tumour; (3) lymphatic drainage and (4) identification of the urinary tract. The most commonly used fluorescent dyes are nonspecific, such as indocyanine green and methylene blue, but there is increasing interest in the development of specific fluorescently labelled molecular markers. Fluorescence imaging is a potentially useful tool for colorectal surgery. Early studies on fluorescence imaging have been promising but larger scale randomised controlled trials are warranted to demonstrate the effectiveness and benefits of using fluorescence imaging routinely. The development of molecular dyes that are specific to targets could significantly increase the potential use of fluorescence imaging during surgery.

Objective The coronavirus pandemic has significantly disrupted the way we deliver healthcare worldwide. We have been flexible and creative in order to continue providing elective colorectal cancer operations and to restart services for benign cases during the recovery period of the pandemic. In this paper, we describe the impact of coronavirus on our elective services and how we have implemented new patient pathways to allow us to continue providing patient care. Methodology Data on major colorectal elective resections was prospectively collected in an Enhanced Recovery After Surgery (ERAS) database. Data on the number of proctology cases and telemed appointments were collected from the hospital theatre information management system and electronic patient record system respectively. Results During the pandemic, there was a complete shift towards cancer cases, with benign services and proctology cases being placed on hold. Hospital length of stay was reduced. We implemented earlier hospital discharge and more intense telephone follow up after elective major surgery. This has not resulted in an increase in post‐operative complications, nor any increase in readmission into hospital. During the recovery phase, we have introduced a higher proportion of telemed consultations, including one‐stop telemed proctology clinics, resulting in straight to tests or investigations. Conclusions We have created a streamlined multi‐disciplinary pathway to reinstate our elective colorectal services as soon as possible and to minimise potential harm caused to patients whose treatment have been delayed. We anticipate many of these changes will be permanently incorporated into our clinical practice once the pandemic is over.

The trend towards minimally invasive surgery extends to the use of localised resection of benign rectal lesions. The advent of interventional colonoscopy has extended the use of polypectomy to larger flat lesions but a variety of techniques are available for the more technically challenging of these benign tumours. Per anal excision of rectal lesions is particularly suitable for patients who would be otherwise unfit for a laparotomy and avoids major pelvic surgery together with its associated complications, such as mortality, anastomotic leakage and stoma formation. Local surgery will also help preserve sphincter function without affecting a patient’s quality of life.

The current gold standard for rectal cancer surgery is performing a total mesorectal excision (TME), which has achieved the best results for minimising local recurrence and improving disease-specific survival. Surgical technology has advanced significantly over the last 30 years, and TME is now being performed through open, laparoscopic, transanal and robotic techniques. The preservation of autonomic nerve function is crucial in maintaining good sexual and urinary function following pelvic surgery. Adequate visualisation and performing surgery within the confines of a limited pelvic space are some of the challenges of rectal cancer surgery. The application of the robot to TME dissection in rectal surgery has several benefits over open and laparoscopic surgery. With better visualisation and access to the pelvis, robotic nerve-sparing TME for rectal cancer could therefore improve the preservation of urinary and sexual function.

Background Iatrogenic ureteric injury is a serious complication of colorectal surgery. Incidence is estimated to be between 0.3 and 1.5%. Of all ureteric injuries, 9% occur during colorectal procedures. Ureteric stents are utilised as a method to reduce the risk of injury; however, these are not without risk and do not guarantee prevention of injury. Fluorescence is a safe and effective alternative for intraoperative ureteric localisation. This proof of principle study aims to assess the use of methylene blue to fluoresce the ureter during colorectal surgery. Method Patients undergoing elective colorectal surgery were included in this open label, non-randomised study. Methylene blue was administered intravenously at varying doses (0.25–1 mg/kg) over 5 min, 10–15 min prior to entering ‘ureteric territory.’ Fluorescence was assessed using the PINPOINT Deep Red laparoscopic system at fixed time points by the surgeon and an independent observer. Results 42 patients received methylene blue; 2 patients were excluded from analysis. Of the 69 ureters assessed, 64 were seen under fluorescence. Of these, 14 were not visible under white light. 50 ureters were observed with both fluorescence and white light with 14 of these being seen earlier with fluorescence. In ten cases, fluorescence revealed the ureter to be in a different location than suspected. Conclusion Fluorescence is a promising method to allow visualisation of the ureter, where it is not identified easily under standard operative conditions, thereby improving safety and reducing operative time and difficulty. Electronic supplementary material The online version of this article (10.1007/s00464-018-6219-8) contains supplementary material, which is available to authorized users.

Background Standard surgical practice for colorectal cancer involves resection of the primary lesion and all draining lymph nodes. Accurate intraoperative assessment of nodal status could allow stratified resectional extent. One-step nucleic acid (OSNA) can provide a rapid method of interrogating nodal tissue, whilst near-infrared (NIR) laparoscopy together with indocyanine green (ICG) can identify relevant nodal tissue intraoperatively. Methods ICG was administered around the tumour endoscopically prior to the operation. Fluorescent nodes identified by NIR were marked and submitted for whole-node OSNA analysis. Further fresh lymph nodes dissected from the standard resection specimen were examined and analysed by both conventional histology and OSNA. In addition, the status of the fluorescent nodes was compared to that of non-ICG nodes to assess their predictive value. Results Sixteen patients were recruited with a total final lymph node count of 287. 78 fresh lymph nodes were identified on fresh dissection for both histological and OSNA assessment with an analytical concordance rate of 98.7% (77/78). OSNA sensitivity was 1 (0.81–1, 95% CI) and specificity 0.98 (0.91–1, 95% CI). Six patients had a total of nine nodes identified intraoperatively by ICG fluorescence. Of these nine nodes, one was positive for metastasis on OSNA. OSNA analysis of the ICG-labelled node matched the final histological nodal stage in 3/6 patients (two being N0 and one N1). The final pathological nodal stage of the other three was N1 or N2, while the ICG nodes were negative. Conclusion OSNA is highly concordant with standard histology, although only a minority of nodes identifiable by full pathological analysis were found for OSNA on fresh dissection. OSNA can be combined with NIR and ICG lymphatic mapping to provide intraoperative assessment of nodal tissue in patients with colorectal cancer.

Background: Our study aimed to identify the search engines and terms commonly used by inflammatory bowel disease (IBD) patients and aimed to assess the quality and readability of these resources.Methods: Patients attending IBD clinic were surveyed, regarding search engines, terms and number of websites viewed. Websites according to these predetermined criteria were identified. Website content was described and quality was assessed using DISCERN. Readability was graded using the Flesch Reading Ease Score (FRES).Results: From 33 survey responses, Google was universally utilised. Forty-two websites met the inclusion criteria (19 for Crohn’s disease (CD), 23 for ulcerative colitis (UC). Only one website originated from Australia. Websites were infrequently updated (CD 21%, UC 17%) within the previous 12 months. Overall readability was poor with a mean FRES of 35.8 (11.8, range 15.7-57.7) for CD and 35.7 (11.3, range 19.4-54.3) for UC websites. Quality was moderate to poor with only five (12%) websites being rated as high quality (2 CD, 3 UC).Conclusions: There is very little Australian based web information available on IBD surgery and overall, it is of a low readability and poor content quality. There is need for the development of patient targeted health literature to help these patients.

Background and aims Anastomotic dehiscence is one of the most feared complications in colorectal surgery leading to significant morbidity and mortality. Progressively lower anastomoses are associated with a greater leak rate. One of the key factors is the perfusion of the bowel to be joined. Presently, surgeons rely on a variety subjective measures to determine anastomotic perfusion and mechanical integrity however these have shortcomings. The aim of this paper is to appraise the literature on the use of fluorescence angiography (FA) in laparoscopic rectal surgery. Materials and methods A Pubmed search was undertaken using terms ‘fluorescence angiography’ and ‘rectal surgery’. The search was expanded using the related articles function. Studies were included if they used FA specifically for rectal surgery. Outcomes of interest including anastomotic leak rate, change of operative strategy and time taken for FA were recorded. Results Eleven papers detailing the use of FA in rectal surgery are outlined demonstrating that this technique may change operative strategy and lead to a reduction in anastomotic leak rate. Conclusion In this paper, we discuss assessment of colorectal blood supply using FA and how this technique holds great potential to detect insufficiently perfused bowel. In so doing, the operator can adjust their operative strategy to mitigate these affects with the aim of reducing the complications of anastomotic leak and stenosis. However, it is highlighted that there is a clear need for randomised controlled trials in order to determine this definitively.

The Internet is a vast resource for patients to search for health information on the treatment of Crohn's disease.This study examines the quality of Web sites that provide information to adults regarding Crohn's disease, including treatment options and surgery.Two search engines (Google and Yahoo) and the search terms "surgery for Crohn's disease" were used. The first 50 sites of each search were assessed. Sites that fulfilled the inclusion criteria were evaluated for content and scored by using the DISCERN instrument, which evaluates the quality of health information on treatment choices.One hundred sites were examined, of which 13 were duplicates. Sixty-two sites provided patient-orientated information. The other sites included 7 scientific articles, 3 blogs, 2 links, 6 forums, 3 video links, and 4 dead links. Of the 62 Web sites that provided patient information for adults, only 15 (24.2%) had been updated within the past 2 years. Only 9 (14.5%) were affiliated with hospitals and clinics. The majority of sites (33, 53.2%) were associated with private companies with commercial interests. Only half of the Web sites provided details on treatment options, and most Web sites did not provide any information on symptoms and procedure details. Just 5 Web sites (8.1%) described the risks of surgery, and only 7 (11.3%) provided any information on the timescale for recovery. Overall, only 1 Web site (1.6%) was identified as being "good" or "excellent" with the use of the DISCERN criteria.Although the internet is constantly evolving, this study captures data at a specific time point. Search results may vary depending on geographical location. This study only assessed English language websites.The quality of patient information on surgery for Crohn's disease is highly variable and generally poor. There is potential for the Internet to provide valuable information, and clinicians should identify high-quality Web sites to guide their patients.

Aim This study examines the quality of websites providing information on ulcerative colitis, including treatment options and surgery. Method Two search engines (Google and Yahoo) and the search term ‘surgery for ulcerative colitis’ were used. The first 50 sites obtained with each search engine were assessed. Sites were evaluated for content and scored using the DISCERN instrument, which evaluates the quality of health information on treatment choices. Results One hundred sites were examined, of which 14 were duplicates. Of the remainder, 58 provided patient-orientated information for adults and one site provided information for surgery in children. The other 27 sites included six scientific articles, three blogs, three links, six resources for clinicians, five fora, two video links and two dead links. Of the 58 websites that provided patient information for adults, only 26 (44.8%) had been updated within the last 2 years. Only 13/58 (22.4%) were affiliated to hospitals and clinics. Most sites (38/58, 65.5%) were associated with private companies with commercial interests. Although most websites contained information on symptoms and treatment options for ulcerative colitis, 37 (63.8%) did not describe any of the risks of surgery. Overall, only seven (12.1%) websites were identified as being ‘good’ or ‘excellent’ using the DISCERN criteria. Conclusion The quality of patient information on surgery for ulcerative colitis is highly variable. There is potential for internet provision of valuable information and clinicians should guide patients with to access high-quality websites.

Purpose The cancer stem cell hypothesis predicts that only a subpopulation of cells within a tumor is responsible for driving growth. If this hypothesis were true, it would have a significant impact on our current treatment of cancer because conventional chemotherapy and radiotherapy target rapidly proliferating cells making up the bulk of the tumor, not specifically cancer stem cells. The aims of this review are to highlight the current evidence supporting the existence of cancer stem cells in colorectal cancer, to consider the relative merits of current cancer stem cell markers, and to discuss the implications of this on our current treatment of cancer. Methods Published scientific articles were selected by searching the PubMed database by use of the terms "colorectal," "cancer," and "stem cells," and by use of the bibliographies of extracted articles. Results and conclusion CD133, a glycosylated cell surface protein, has been demonstrated to isolate for a subpopulation of colorectal tumor cells enriched in cancer stem cells. However, only 1 in 262 CD133+ cells are able to initiate tumors. Other cancer stem cell markers have been investigated, but an overall need exists to identify more specific markers to allow further characterization of these cancer stem cells. We discuss how increased understanding of the distribution and behavior of cancer stem cells within tumors could have significant implications for the management of colorectal cancer, including screening, resection margins, sentinel node biopsy, determination of prognosis, and the development of novel therapeutic targets.

Background The Internet is a vast resource available for patients to obtain health information. Objective This study examines the quality of Web sites that provide information on diverticular disease, treatment options, and surgery. Design Two search engines (Google and Yahoo) and the search terms "surgery and diverticular disease" and "surgery and diverticulitis" were used. The first 50 sites of each search were assessed. Sites that fulfilled the inclusion criteria were evaluated for content and scored by using the DISCERN instrument, which evaluates the quality of health information on treatment choices. Results Two hundred sites were examined, of which 60 (30%) provided patient-orientated information. 50 sites (25%) were duplicated, 7 (3.5%) were links, 10 (5%) were advertisements, 14 (7%) were resources for clinicians, 9 (4.5%) were message forums, 27 (13.5%) were articles, and 15 (7.5%) were dead links. Of the 60 Web sites that provided patient information, only 10 (16.7%) had been updated within the past 2 years. Seventeen (28.3%) sites were affiliated with hospitals and clinics, but another 17 (28.3%) sites were associated with private companies with commercial interests. Although most Web sites contained information on symptoms, complications, investigations, and treatment options of diverticular disease, 20 (33.3%) did not describe any of the risks of surgery, and 45 (75%) did not provide information on the timescale of recovery postoperatively. Eighteen sites did not provide balanced information on treatment options; of these, 7 were biased toward medical treatment and 6 focused on laparoscopic surgery. Overall, only 22 (36.7%) were identified as being "good" or "excellent" with the use of the DISCERN criteria. Conclusions The quality of patient information on surgery for diverticular disease is highly variable, and Web sites that are sponsored by private companies may be biased in discussing treatment options. There is potential for the Internet to provide valuable information, and clinicians should guide patients to access high-quality Web sites.

Lymph node staging in colorectal cancer (CRC) is established by histological examination. Molecular techniques, such as one-step nucleic acid amplification (OSNA), have been recommended by NICE1 for intraoperative sentinel node assessment in breast cancer. OSNA is a relatively novel and simple molecular technique that uses a reverse-transcriptase loop-mediated isothermal amplification (RT-LAMP) reaction to detect tumour specific (CK19) mRNA in lymph nodes. We aim to provide unbiased data on the diagnostic accuracy of OSNA in detecting CRC nodal metastases and feedback the practicalities of running such a service in an National Health Service (NHS) cellular pathology department. Consent was sought from consecutive patients undergoing elective resection for any stage CRC over a 14-month period (November 2013–December 2014). Stented tumours and perforated cases were excluded. Resected specimens were received fresh, inked according to standard guidelines and lymph nodes were dissected. Each harvested node was bisected—one half was fixed in 10% formalin for routine histology and the other was snap-frozen in liquid nitrogen and stored at −80°C for OSNA processing. The remaining specimen was fixed and subsequently dissected for standard histology. OSNA assaying was performed as per manufacturers' instructions. Lymph nodes weighing >0.05 g were analysed in a single assay and those

Aim Conventional white-light endoscopy is currently the gold standard for the detection and treatment of colorectal polyps. However, up to a fifth of polyps may be missed on initial examination, especially flat and small mucosal lesions. This study reviews the literature reporting on the use of new advances in endoscopic visualization. Method Literature searches were performed on PubMed using the terms ‘chromoendoscopy’, ‘narrow-band imaging’ (NBI), ‘autofluorescence imaging’ (AFI), ‘Fujinon Intelligent Colour Enhancement’ (FICE), ‘i-Scan colonoscopy’, ‘zoom colonoscopy’ and ‘confocal laser endomicroscopy’ (CLE). We focused on systematic reviews, national guidelines and randomized controlled trials written in English. Studies were assessed for methodological quality using QUADAS. Prospective studies assessing new technology were also reviewed. Further publications were identified from reference lists. Results Chromoendoscopy increases the detection of neoplastic polyps compared with conventional colonoscopy. NBI avoids the use of additional dyes and enhances the vascular network of capillaries surrounding the crypts, increasing the adenoma detection rate and the ability to distinguish between neoplastic and non-neoplastic lesions. FICE, AFI and i-Scan are new developments that improve tissue contrast. Zoom endoscopy may be combined with different modalities to help further characterize colonic lesions. CLE provides live in vivo high-resolution optical sections of tissue and may be particularly useful in the surveillance of patients with long-standing ulcerative colitis, reducing the number of random biopsies. Conclusion Although there is mounting evidence that these new technologies are superior to conventional endoscopy, current guidelines are limited. Further large-scale randomized controlled trials comparing these modalities in different patient subpopulations are warranted.

The management of patients with pre-existing tuberculosis (TB) undergoing liver transplantation is challenging. Cautious immunosuppression is required to prevent reactivation of disease, and second-line anti-tuberculous treatment may be necessary to prevent graft hepatotoxicity. Furthermore, liver transplantation in the context of isoniazid-resistant TB has seldom been reported. We report on a 44-year-old man with recent isoniazid-resistant extra-pulmonary TB who developed subacute hepatic failure requiring emergency liver transplantation and treatment with second-line anti-tuberculous therapy. We demonstrate that patients who have pre-existing TB can be successfully treated with alternative anti-tuberculous medication while under immunosuppression post transplantation. Pre-existing TB, including resistant strains, should not be an absolute contraindication to liver transplantation.

Colorectal surgery is one of the most common procedures performed around the world with more than 600,000 operations each year in the United States, and more than a million worldwide. In the past two decades, there has been a clear trend toward minimal access and surgeons have embraced this evolution. Widespread adoption of advanced minimally invasive procedures is often limited by procedural complexity and the need for specific technical skills. Furthermore, the loss of 3D vision, limited overview of the surgical field, and diminished tactile sensation make major colorectal procedures more challenging and have an impact on the surgeons' learning curves. New technologies are emerging that can compensate for some of the sensory losses associated with laparoscopy. High-definition picture acquisition, 3D camera systems, and the use of biomarkers will allow improved identification of the target structures and help differentiate them from surrounding tissues. In this article, we describe some of the new technologies available and, in particular, focus on the possible implications of biomarkers and fluorescent laparoscopic imaging.

We describe the case of an 81-year-old woman with large bowel-obstruction caused by an impacted gallstone. An 81-year-old, Caucasian, fully independent woman without significant comorbidities presented with absolute constipation, faecal vomiting and abdominal pain. Abdominal radiography revealed dilated small bowel, and a subsequent contrast CT demonstrated a 2.5 cm gallstone in the sigmoid colon. This is believed to have entered the transverse colon via a cholecyst-colonic fistula, and then migrated to a section of sigmoid colon affected by diverticular disease, where it became impacted. Two sigmoidoscopic removals were attempted but were unsuccessful as the gallstone9s size prevented removal with an endoscopic basket. A laparotomy was performed and the stone extracted via a sigmoid enterotomy. No covering stoma was formed, and following 48 h on intensive trauma unit and a short ward-based stay for rehabilitation, the patient was discharged home and is currently doing well.

Introduction Haemorrhoids are the most common benign condition seen by colorectal surgeons. At clinic appointments, advice given about lifestyle modification or surgical interventions may not be understood fully by patients. Patients may use the internet for further research into their condition. However, the quality of such information has not been investigated before. This study assessed the quality of patient information on surgical treatment of haemorrhoids on the internet. Methods Four searches were carried out using the search terms ‘surgery for haemorrhoids’ and ‘surgery for piles’ on two search engines (Google and Yahoo). The first 50 results for each search were assessed. Sites were evaluated using the DISCERN instrument. Results In total, 200 websites were assessed, of which 144 fulfilled the inclusion criteria. Of these, 63 (44%) were sponsored by herbal remedies for haemorrhoids. Eighty-nine (62%) mentioned conservative treatment options but eleven (8%) did not include surgery in their treatment options. Only 38 sites (27%) mentioned recurrence of haemorrhoids following surgery and 28 sites (20%) did not list any complications. Overall, 19 websites (14%) were judged as being of high quality, 66 (45%) as moderate quality and 58 (40%) as low quality. Conclusions The quality of information on the internet is highly variable and a significant proportion of websites assessed are poor. The majority of websites are sponsored by private companies selling alternative treatments for haemorrhoids. Clinicians should be prepared to advise their patients which websites can provide high-quality information on the surgical treatment of haemorrhoids.

Background: Myofibroblasts have an important role in regulating the normal colorectal stem cell niche. While the activation of myofibroblasts in primary colorectal cancers has been previously described, myofibroblast activation in lymph node metastases has not been described before. Methods: Paraffin-embedded lymph node sections from patients with macrometastases, micrometastases and isolated tumour cells were stained to identify myofibroblasts and to characterise the distribution of different cell types in tumour-containing lymph nodes. The extent of myofibroblast presence was quantified and compared with the size of the metastasis and degree of proliferation and differentiation of the cancer cells. Results: We show substantial activation of myofibroblasts in the presence of colorectal metastases in lymph nodes, which is intimately associated with glandular structures, both in micro- and macrometastases. The degree of activation is positively associated with the size of the metastases and the proportion of Ki67+ve cancer cells, and negatively associated with the degree of enterocyte differentiation as measured by CK20 expression. Conclusion: The substantial activation of myofibroblasts in tumour-containing lymph nodes strongly suggests that these metastatic cancer cells are still significantly dependent on their microenvironment. Further understanding of these epithelial–mesenchymal interactions could lead to the development of new therapies in metastatic disease.

Introduction Iatrogenic ureteric injury is a serious complication of colorectal surgery. Fluorescence image guided surgery (FIGS) is an expanding field and can potentially make operations safer for patients and prevent inadvertent ureteric injury. Intravenously administered methylene blue is excreted renally and concentrated in the urine. It is fluorescent at 660nm and can therefore be used to locate ureters intraoperatively using fluorescence enabled cameras and laparoscopes. The aim of this study is to assess the use of methylene blue under fluorescence to identify ureters during laparoscopic and open colorectal surgery. The primary objective is to compare ureter identification using white light versus fluorescence in each patient. The secondary objectives are to quantify the level of fluorescence at different time points following administration of methylene blue and to work out the optimum time to visualise the ureters. Method All adult patients undergoing either laparoscopic or open colorectal surgery were considered for inclusion into this study. Exclusion criteria were pregnancy, significant renal or hepatic impairment, and patients taking SSRIs with a risk of developing serotonin syndrome. Between 0.25 – 1 mg/kg of methylene blue was administered intravenously during the operation. Background and peak fluorescence were measured at multiple time points during the procedure, using custom-made fluorescence-enabled laparoscopes and open cameras that could detect fluorescence at 660 nm. Results 8 consecutive patients undergoing colorectal surgery were recruited into this study, of which 6 were laparoscopic and 2 were open procedures. Out of 11 ureters, 10 were successfully visualised under fluorescence (example shown in image below). The mean time to peak fluorescence was 14.5 min after intravenous methylene blue injection. There was a low background signal, and the mean signal to background ratio was 2.74. Fluorescence could be detected up to 75 min after injection. This technique was considered useful in 4 patients: in one case, the ureter was more medial than initially thought, in another case, the ureter was not seen on white light but was seen under fluorescence, and in two cases, the ureters were traced from the pelvic brim all the way to the kidneys. There were no complications after administration of methylene blue. Conclusion The use of methylene blue is a safe and simple technique to identify the location of ureters under fluorescence. Larger clinical studies are required to identify which subsets of patients would benefit from this form of fluorescence image guided surgery. Disclosure of interest None Declared.

Background Spinal cord injury is a serious and debilitating condition, affecting millions of people worldwide. Long seen as a permanent injury, recent advances in stem cell research have brought closer the possibility of repairing the spinal cord. One such approach involves injecting oligodendrocyte progenitor cells, derived from human embryonic stem cells, into the injured spinal cord in the hope that they will initiate repair. A phase I clinical trial of this therapy was started in mid 2010 and is currently underway. Discussion The theory underlying this approach is that these myelinating progenitors will phenotypically replace myelin lost during injury whilst helping to promote a repair environment in the lesion. However, the importance of demyelination in the pathogenesis of human spinal cord injury is a contentious issue and a body of literature suggests that it is only a minor factor in the overall injury process. Summary This review examines the validity of the theory underpinning the on-going clinical trial as well as analysing published data from animal models and finally discussing issues surrounding safety and purity in order to assess the potential of this approach to successfully treat acute human spinal cord injury.

4124 Background: Cancer stem cells are defined as cells within a tumour that are able to self-renew and differentiate into all cell lineages within that tumour. With our extensive panel of colorectal cell lines, our aims are: 1) To characterise and isolate cancer stem cells based on stem cell markers, morphological appearances and the ability to form multiple lineages; 2) To understand how cancer stem cells drive tumour growth and progression. Methods: 1) Fluorescent Activated Cell Sorting (FACS); 2) In vitro soft agar clonogenic and Matrigel differentiation assays; 3) In vivo tumourigenic NOD/SCID mice assay; 4) Confocal immunofluorescence imaging. Results: 1) A subpopulation of cells can differentiate into crypt-like megacolonies, retaining the ability to self-renew and differentiate. SW1222 cell line forms heterogeneous colonies when single cells are plated in Matrigel. Megacolonies can both self-renew and form terminally differentiated small colonies, whereas small colonies cannot form megacolonies. Megacolonies develop crypt-like structures and increase their expression of differentiation markers (CDX-1, CK-20) over time. Experiments are currently under way to confirm that cells from megacolonies are able to initiate tumours in NOD/SCID mice. Some cell lines retain the ability to differentiate into both neuroendocrine and epithelial lineages. 2) CD44+CD24+ enriches for the cancer stem cell population. Colorectal cancer cell lines HCT116, HT29, LS180, LS174T and SW1222 express both CD44 and CD24. The CD44+CD24+ subpopulation is the most clonogenic. In SW1222, CD44+CD24+ cells enrich for megacolonies and can reform all four CD44/CD24 subpopulations. 3) Hypoxia reduces differentiation, increases stem-like phenotype and enhances clonogenicity. Hypoxia increases the proportion of undifferentiated colorectal cancer cells when plated on Matrigel and increases clonogenicity. Conclusions: 1) Colorectal cancer cell lines contain subpopulations of cells that have the ability to self-renew, differentiate and drive tumour growth, and may be characterised by their cell surface markers and colony morphology. 2) CD44+CD24+ can be used as markers for colorectal cancer stem cells. 3) Hypoxia increases the stem-like phenotype of cancer cells, reduces differentiation and increases clonogenicity. No significant financial relationships to disclose.