Treatment of Abdominal Aortic Aneurysm Utilizing Adipose-Derived Mesenchymal Stem Cells in a Porcine Model.

INTRODUCTION: The current treatment paradigm of abdominal aortic aneurysms (AAA) focuses on observing patients until their disease reaches certain thresholds for intervention, with no preceding treatment available. There is an opportunity to develop novel therapies to prevent further aneurysmal growth and decrease the risk of a highly morbid rupture. We used a porcine model of aortic dilation to assess the ability of human adipose-derived mesenchymal stem cells (MSCs) to attenuate aortic dilation. MATERIALS AND METHODS: Twelve Yorkshire pigs received periadventitial injections (collagenase and elastase) into a 4-cm segment of infrarenal aorta. Animals were treated with either 1 × 106 MSCs placed onto Gelfoam or treated with media as a control. Aortic diameters were measured at the time of surgery and monitored at postoperative day (POD) 7 and 14 with ultrasound. Animals were sacrificed on POD 21. Aortic tissue was harvested for histopathological analyses and immunohistochemistry. Groups were compared with paired t-tests or Mann-Whitney U-tests. RESULTS: All animals survived until POD 21. The mean aortic diameter was reduced in the aortic dilation + MSC treatment group compared to aortic dilation control animals (1.10 ± 0.126 versus 1.48 cm ± 0.151, P < 0.001). Aortic media thickness was reduced in the aortic dilation group compared to the aortic dilation + MSC group (609.14 IQR 445.21-692.93 µm versus 643.55 IQR 560.91-733.88 µm, P = 0.0048). There was a significant decrease in the content of collagen and alpha-smooth muscle actin and elastin perturbation in the aortic dilation group as compared to the aortic dilation + MSC group. Immunohistochemistry demonstrated an increased level of vascular endothelial growth factor, tissue inhibitor of matrix metalloproteinase 1, and tissue inhibitor of matrix metalloproteinase 3 expression in the aorta of aortic dilation + MSC animals. CONCLUSIONS: Stem cell therapy suppressed the aortic dilation in a porcine model. Animals from the aortic dilation group showed more diseased gross features, histologic changes, and biochemical properties of the aorta compared to that of the aortic dilation + MSC treated animals. This novel finding should prompt further investigation into translatable drug and cell therapies for aneurysmal disease.

Effect of preoperative radiation on free flap outcomes for head and neck reconstruction: An updated systematic review and meta-analysis.

BACKGROUND: There is an ongoing debate about whether neoadjuvant radiation therapy is associated with higher rates of postoperative complications after head and neck reconstruction. Herle et al. conducted a systematic review in 2014 of 24 studies, finding higher complication rates in irradiated fields. We sought to perform an exhaustive updated systematic review and meta-analysis. METHODS: We conducted an updated systematic review of the literature, as outlined in our protocol, which was registered on PROSPERO. Databases included Medline, Embase, Cochrane Central, and Web of Science. There were no limits placed on the date range, place of publication, or origin. Exclusion criteria included patients less than 18 years of age, studies with less than 20 participants (n < 20), case studies, skull base reconstructions, and local tissue rearrangements. The combined results of the studies and relative risks (RR) were calculated. RESULTS: 53 studies were included for analysis, including 5,086 free flaps in an irradiated field, and 9,110 free flaps in a non-irradiated field. Of the 53 studies, 21 studies overlapped with those discussed in Herle et al.'s study, with a total of 32 additional studies. Neoadjuvant radiation was found to be a statistically significant risk factor for postoperative complications (RR 1.579, P < 0.001), total flap failure (RR, 1.565; P < 0.001), and fistula (RR, 1.810; P < 0.001). Our work reaffirmed the findings of the Herle et al. CONCLUSION: Preoperative radiation was associated with a statistically significant increase in the risk of total flap failure, fistula, and total complications but not partial flap failure. These high-morbidity complications must be taken into consideration when determining which patients should receive neoadjuvant radiation therapy.

Development of a Model for Abdominal Aortic Aneurysms in Swine.

INTRODUCTION: Producing a reliable large-animal model of AAA has proven challenging. We sought to create a reproducible swine model of AAA using enzymatic degradation of the aortic wall. METHODS: Twelve male Yorkshire swine received periadventitial injections of type 1 collagenase and porcine pancreatic elastase into a 4 cm segment of infrarenal aorta. Nine survived until postoperative day (POD) 21. Aortic growth was monitored at 7 and 14 days using ultrasound. The animals were euthanized on POD 21, and the suprarenal (control) and infrarenal aorta were harvested for analysis, after gross measurement of aortic diameter (AD). Tensile strength was measured and additional segments were collected for histopathological analysis. PCR of matrix metalloproteinases (MMP9) was conducted. Groups were compared with paired t-tests, or ANOVA, where appropriate. RESULTS: Average percent growth of AD at POD 21 for treated segments was 27% versus 4.5% for control tissue. The average difference in AD by subject, was 26.7% (P<0.001). Aortic medial thickness was decreased in treated tissue; 235 µm versus 645 µm (P<0.0001). Quantities of both medial elastin fibers, and smooth muscles cells were decreased in treated tissue; 1.8% compared to 9.9% (P<0.0001), and 24% versus 37.4%, respectively. Tensile strength was also decreased in treated tissue; 16.7 MPa versus 29.5 MPa (P=0.0002). A 12-fold increase in expression of MMP9 mRNA was also demonstrated in aneurysmal tissue (P=0.002) CONCLUSION: A reproducible, large-animal model of AAA, with anatomical, histopathological, and biomechanical properties that are clinically translatable, can be achieved with extraluminal enzymatic degradation.

Effect of Daily Dosage of Morphine Milligram Equivalents on Free Flap Complications: A Single-Institution Retrospective Study.

INTRODUCTION: There appears to be an association between preoperative opioid use and postoperative complications. We sought to determine whether patients with a history of chronic opiate use (defined as 3 months or more of sustained use) prior to undergoing free flap surgery have higher rates of 30-day complications. METHODS: A retrospective review of patients undergoing free flaps from 2015 to 2020 was performed. Patient characteristics were analyzed, including daily preoperative dose of opiates, which were then converted to morphine milligram equivalents; intra-operative variables such as estimated blood loss and operating room time; and 30-day outcomes, including wound and flap complications, return to the operating room, and readmissions. RESULTS: One hundred fifty-five patients received 160 free flaps. Of these flaps, 50/160 (31%) were performed on patients with an opiate prescription for at least three months prior to surgery. Using multivariable analysis, morphine milligram equivalents, a surrogate for opioid dose, were significantly associated with flap complications (odds ratio (OR) 1.011, 95% confidence interval (CI) 1.003-1.020, p<0.01), partial flap loss (OR 1.010, 95% CI 1.003-1.019, p<0.01), and surgical site infections (OR 1.017, 95% CI 1.007-1.027, p<0.01). Additionally, estimated blood loss was associated with partial flap loss (OR 4.838, 95% CI 1.589-14.728, p<0.006), and operating room time was also associated with flap complications (OR 1.337, 95% CI 1.152-1.150, p<0.01). CONCLUSION: Chronic preoperative opioid use is common for free flap surgery, and according to our single-center experience, higher daily doses are a risk factor for flap complications and surgical site infections. These findings add to the growing body of evidence that opioid use is a modifiable risk factor that may increase surgical morbidity.

Role of metastasectomy for liver metastasis in stage IV anal cancer.

INTRODUCTION: There is a paucity of data on the role of metastasectomy for metastatic anal cancer on survival outcomes. We aim to define the role of metastasectomy in stage IV anal cancer. METHODS: National Cancer Database (NCDB) from 2004 to 2014 was accessed to include patients with metastatic anal cancer, excluding adenocarcinoma, neuroendocrine, and 'other' histologies. We compared patients undergoing metastasectomy (n = 165) to those who did not have metastasectomy (n = 2093) by age, sex, cancer grade, and site of metastasis, including metastasis to bone, liver, and lung, using chi-square analysis. The primary outcome was overall survival. RESULTS: Patients had equal distribution of metastatic sites between those who underwent metastasectomy versus no metastasectomy: bone (7.64% vs 4.85%, p = 0.22), brain (0.24% vs 0%, p = 1.0), liver (23.22% vs 29.70%, p = 0.07), and lung (11.85% vs 9.09%, p = 0.38). Survival following metastasectomy was increased at one year (71% vs. 61%, p = 0.016), two years (50% vs. 38%, p = 0.014), and five years (30% vs. 19%, p = 0.025). Median overall survival was increased (23 months vs. 16 months; p = 0.015) for patients with metastasectomy. Survival increases were demonstrated only in the group with liver metastasis undergoing metastasectomy. When stratifying for liver metastases only, median overall survival time was further increased (34 months vs. 16 months; p < 0.0001) following metastasectomy. CONCLUSION: These results demonstrate a survival benefit for hepatic metastasectomy in stage IV anal cancer. Our findings demonstrate a potential survival benefit in highly select patients with metastatic anal cancer to the liver. These findings support further investigation in a randomized clinical trial to delineate these findings.

Role of marijuana components on the regenerative ability of stem cells.

Stem cell therapy promotes tissue regeneration and wound healing. Efforts have been made to prime stem cells to enhance their regenerative abilities. Certain marijuana components, namely the non-psychoactive cannabidiol (CBD) and psychoactive tetrahydrocannabinol (THC), are defined as immunomodulators.9 We test whether two sources of stem cells, primed with CBD or THC, would demonstrate improved regenerative abilities. Human adipose-derived stem cells (ASCs) and bone marrow-derived stem cells (BMDSCs), not obtained from the same individual, were treated with low (300 nM) or high (3 µM) concentration CBD. Porcine ASCs and BMDSCs were isolated from a single pig, and treated with either low or high concentrations of CBD or THC. Transwell migration and MTT proliferation assays were performed on the human ASCs and BMDSCs. Also, transwell migration assay was performed on the porcine ASCs and BMDSCs. Finally, a wound healing scratch assay in porcine primary fibroblasts (PFs) was performed, co-cultured with the cannabinoid-treated ASCs. CBD priming at low concentration induces migration by 180% (P < .01) in porcine ASCs, and by only 93% (P < .02) in porcine BMDSCs. In porcine stem cells, THC priming at low concentration induces migration by 91.6% (P < .01) in ASCs but by only 44.3% (P < .03) in BMDSCs. Compared to PFs co-cultured with untreated ASCs, PFs co-cultured with low CBD-primed ASCs had 75% faster wound closure at 18 hours (P < .01). CBD and THC priming of ASCs and BMDSCs, particularly at lower doses, enhances a number of regenerative parameters, suggesting that these major marijuana components may improve stem cell-based therapies. SIGNIFICANCE OF THE STUDY: Our study demonstrates that cannabinoids can enhance the regenerative capacity of two major sources of stem cells, adipose- and bone marrow-derived, from human and porcine donors. Stem cell isolation and expansion is invasive, costly and time consuming. Stem cells with improved regenerative properties may be effective in the treatment of acute or chronic wounds. This is the first study to compare the priming potential of two sources of stem cells from the same animal, with the same genetic and epigenetic profile, as well as the first to prime with THC.

Validation of the Gail model for predicting individual breast cancer risk in a prospective nationwide study of 28,104 Singapore women.

INTRODUCTION: The Gail model (GM) is a risk-assessment model used in individual estimation of the absolute risk of invasive breast cancer, and has been applied to both clinical counselling and breast cancer prevention studies. Although the GM has been validated in several Western studies, its applicability outside North America and Europe remains uncertain. The Singapore Breast Cancer Screening Project (SBCSP) is a nation-wide prospective trial of screening mammography conducted between Oct 1994 and Feb 1997, and is the only such trial conducted outside North America and Europe to date. With the long-term outcomes from this study, we sought to evaluate the performance of GM in prediction of individual breast cancer risk in a Asian developed country. METHODS: The study population consisted of 28,104 women aged 50 to 64 years who participated in the SBSCP and did not have breast cancer detected during screening. The national cancer registry was used to identify incident cases of breast cancer. To evaluate the performance of the GM, we compared the expected number of invasive breast cancer cases predicted by the model to the actual number of cases observed within 5-year and 10-year follow-up. Pearson's Chi-square test was used to test the goodness of fit between the expected and observed cases of invasive breast cancers. RESULTS: The ratio of expected to observed number of invasive breast cancer cases within 5 years from screening was 2.51 (95% confidence interval 2.14 - 2.96). The GM over-estimated breast cancer risk across all age groups, with the discrepancy being highest among older women aged 60 - 64 years (E/O = 3.53, 95% CI = 2.57-4.85). The model also over-estimated risk for the upper 80% of women with highest predicted risk. The overall E/O ratio for the 10-year predicted breast cancer risk was 1.85 (1.68-2.04). CONCLUSIONS: The GM over-predicts the risk of invasive breast cancer in the setting of a developed Asian country as demonstrated in a large prospective trial, with the largest difference seen in older women aged between 60 and 64 years old. The reason for the discrepancy is likely to be multifactorial, including a truly lower prevalence of breast cancer, as well as lower mammographic screening prevalence locally.

Molecular epidemiology of vancomycin-resistant enterococci in Singapore.

AIMS: To characterise the mechanism of glycopeptide resistance, genetic relatedness, and pathogenicity factors in isolates of vancomycin-resistant enterococci (VRE) in Singapore. METHODS: A total of 292 Enterococcus faecium and 17 Enterococcus faecalis were isolated from humans, and five E. faecium, two Enterococcus durans, two Enterococcus flavescens, one Enterococcus casseliflavus, and one Enterococcus gallinarum from chickens. The mechanism of glycopeptide resistance and pathogenicity factors were studied by PCR and the genetic relatedness determined by pulsed-field gel electrophoresis (PFGE), multi-locus variable number tandem repeat analysis (MLVA), and Tn1546 analysis. RESULTS: There were five outbreak clones among the vancomycin-resistant E. faecium with one clone predominant. Four of the clones were vanB positive, and only one clone carried vanA. All outbreak clones were esp gene positive. Sporadic human isolates and chicken isolates were vanA positive and did not contain any pathogenicity genes. The situation was reversed in vancomycin-resistant E. faecalis where almost all isolates were vanA positive. CONCLUSIONS: Most VRE in Singapore is hospital associated with a small number of clones of esp-positive vanB E. faecium responsible for the majority of isolates.