Derivation of thyroid progenitors from human induced pluripotent stem cells

Objective

Despite the availability of synthetic thyroid hormone for therapeutic use, a significant number of patients with hypothyroidism do not feel well on replacement doses of thyroid hormones suggesting that better-individualized therapy is needed. For this reason, hypothyroidism resulting from congenital lack of functional thyrocytes, surgical tissue removal, or gland ablation, represents a particularly attractive endocrine disease target that may be conceivably cured by transplantation of long-lived functional thyroid progenitors or mature follicular epithelial cells.

Methods

To generate thyroid follicular progenitors from human induced pluripotent stem cells (hiPSCs), we sought to develop a directed differentiation approach by activating or inhibiting endogenous developmental signaling pathways previously identified in the mouse. To facilitate tracking and purification of candidate human thyroid progenitors, we engineered a hiPSC-line carrying a tdTomato reporter targeted to the PAX8 locus and a GFP reporter targeted to the NKX2-1 locus.

Results

We adapted our published in vitro differentiation protocol previously used to differentiate mouse PSCs into thyroid progenitors and observed tdTomato/GFP co-expressing cells first emerging from our hiPSC line by day 12 of culture and persisting for at least 2 months of further culture in thyroid maturation media, supplemented with TSH. Thus, we profiled all cells deriving from hiPSCs by single-cell RNA sequencing >6,000 cells captured on days 12 and 29 of in vitro differentiation. At day 12, tdTomato/GFP co-expression was observed in 12% of all cells and these cells appeared to be early thyroid follicular progenitors as they uniquely co-expressed the tetrad of thyroid lineage selective transcription factors, NKX2-1, PAX8, FOXE1, and HHEX. By day 29 tdTomato+/GFP+ cells represented 69% of all cells and had upregulated TG, TSHR, NIS and TPO expression in addition to the previously described four thyroid lineage markers, suggesting time-dependent differentiation and maturation of thyroid follicular epithelial cells.

Conclusion

Thus, we have employed a novel hiPSC line to optimize a protocol able to generate human thyroid progenitors and mature follicular epithelial cells, representing a purifiable source of human thyroid lineage cells whose functional and thyroid reconstituting potential can be tested in vivo in animal models of hypothyroidism.

Comparison of surgical outcomes in elective sigmoid resection for diverticulitis in different indication-specific strategies: A propensity-score matched cohort study with 636 patients

Objective

Comparing different surgical guidelines for recurrent uncomplicated diverticulitis, a careful benefit-risk assessment is recommended although different approaches giving the indication for surgery exists. The purpose of this study was to evaluate the impact of indications-specific strategies on surgical outcomes allowing adequate benefit-risk consulting.

Methods

All patients undergoing elective colonic resection for diverticulitis between January 2011 and March 2020 in our institution were included. They were divided into two groups based on the strategy for surgical indication: relative surgery indication group (RSI; CDD (classification of diverticula disease) Type 2a, 3a and 3b, n = 585) and absolute surgery indication group (ASI; CDD Type 2b and 3c, n = 318). Propensity score-matching (PSM) was applied at a ratio of 1:1 to compare the RSI and the ASI group.

Results

In the univariate analysis, RSI patients were younger (62±10.4 vs. 67.7±11.4, p<0.05), had a higher physical status (ASA score 1 or 2 in 80.7% vs. 60.8%, p<0.05), were less immunosuppressed (3.4% vs. 6.9%, p<0.05) and suffered less from coronary heart disease (3.8% vs. 7.2%, p<0.05). After PSM, 318 vs. 318 patients were selected and baseline characteristics resulted comparable. The proportion of laparoscopic resection was 94.7% in RSI versus 84.6% in ASI (p<0.05) and the conversion rate to open surgery for laparoscopic resection was 5.0% in RSI and 13.8% in ASI (p<0.05). Intraoperative complications were rare in both groups (3.1% vs. 5.3%, p=0.24). Mean operation time was shorter in RSI (211±62 vs. 229±72, p<0.05). Major morbidity (Clavien/Dindo ≥3b) occurred less frequently in RSI (3.8% vs. 10.1%, p<0.05) and the overall comprehensive complications index (CCI) was lower in RSI (9.4±12.2 vs. 12.9±14.9, p<0.05). Anastomotic insufficiency occurred in 0.9% in RSI and in 2.5% in ASI (p=0.22). A defunctioning stoma was received by 0.9% in RSI and 11.0% in ASI (p<0.05).

Conclusion

Our study demonstrates that even after PSM analysis patients with RSI in contrast to patients with more advanced diverticular disease have a lower risk of suffering from postoperative overall morbidity and major morbidities as well as the risk of receiving a temporary stoma. These observations should be considered when counselling patients with an equivocal indication for surgery for diverticular disease.

High expression of CD34 protein in stage IIA rectal cancer is independently associated with better prognosis

Objective

Colorectal cancer (CRC) remains the third most common cause of death from malignancies, while 30% of all these tumors develop in the rectum. The proximity of the rectum to vital structures, and in some cases the use of neoadjuvant treatment, make the surgical resection of this tumor a great challenge even for highly qualified surgeons. Understanding the mechanisms of rectal cancer (RC) development could lead to new concepts in the approach of diagnosis, prognosis, and eventually treatment of this disease. Despite the fact that TNM classification represents the gold standard tool for the staging of RC, a significant number of studies has recently focused on the association between the tumor microenvironment and RC. CD34 is a transmembrane phosphoglycoprotein expressed on human hematopoietic progenitor and vascular endothelial cells, as well in malignant tissues. It has also been shown to be involved in tumor invasion and angiogenesis. Because of the controversial data , we examined the expression of CD34 protein in RC specimens after stratifying the patients according to their UICC stage.

Methods

In our retrospective study, we included 364 patients with unselected, clinically annotated primary RC specimens. We analyzed a tissue microarray (TMA) of these specimens by immunohistochemistry (IHC) for the expression of CD34 protein by tumor cells.

Results

After stratifying the patients in nodal negative and positive groups, we found that the patients with Stage IIA tumors and high expression of CD34 protein had a favorable 5-year overall survival rate (53%; 95%CI = 40.0 – 65.1%) compared to tumors without expression of CD34 protein (26%; 95%CI = 10.7 – 44.6%, p = 0.003). Univariate and multivariate Hazard Cox regression survival analysis revealed that the combined the expression of CD34 protein was an independent, favorable, prognostic marker for overall survival in the stage IIA RC (HR = 0.39, 95%CI = 0.19 – 0.79; p = 0.009).

Conclusion

Our data show that the expression of CD34 protein represents an independent, favorable, prognostic condition in nodal negative stage IIA RC. Thereby, we provide novel insights into the prognostic role of the tumor microenvironment in RC that might help in the development of novel treatment modalities by its modification.

Left lower transverse incision versus Pfannenstiel-Kerr incision for specimen extraction in laparoscopic sigmoidectomy: a match pair analysis

OBJECTIVE

The ideal location of specimen extraction in laparoscopic-assisted colorectal surgery is still debatable. The aim of this study was to compare the incidence of incisional hernias and surgical site infections in patients undergoing elective laparoscopic resection for recurrent sigmoid diverticulitis by performing specimen extraction through left lower transverse incision or Pfannenstiel-Kerr incision.

METHODS

A total of 269 patients operated between January 2014 and December 2017 were retrospectively screened for inclusion in the study. Patients with specimen extraction through left lower transverse incision (LLT) and patients with specimen extraction through Pfannenstiel-K incision (P-K) were matched in 1:1 proportion regarding age, sex, comorbidities, and previous abdominal surgery. The incidence of incisional hernias and surgical site infections were compared by using Fisher's exact test.

RESULTS

After matching 77 patients in the LLT group and 77 patients in the P-K group, they were found to be homogenous regarding the above mentioned descriptive characteristics. No patients in the P-K group developed an incisional hernia compared with 10 patients (13%) in the LLT group (p = 0.001). All these patients required hernia repair with mesh augmentation. The rate of surgical site infections was 1/77 in the P-K group and 0/77 in the LLT group (p = 1.0). In the P-K group, a wound protector was used in 86% of patients whereas in the LLT group, 39% of the wounds were protected during specimen extraction (p < 0.0001).

CONCLUSION

The Pfannenstiel-Kerr incision may be the preferred extraction site compared with the left lower transverse incision given the significant reduction of the risk of incisional hernias.

Current clostridium difficile treatments: Lessons that need to be learned from the clinical trials

Clostridium difficile infection (CDI) is the most common infectious disease cause of nosocomial diarrhea in adults in developed countries. Judging from the clinical trials on drugs used in CDIs, no approved treatment for recurrences exists, possibly indicating that a combination of treatment approaches are mandatory especially in severe infections, with current studies not being fully representative. Among the new strategies researched intensively fidaxomicin is presented, which demonstrates reduced CDI recurrences. Moreover, biotherapeutic strategies, mainly fecal microbiota transplantation but also competitive inhibition with non-toxigenic strains of C. difficile, and finally monoclonal antibodies against C. difficile toxins which offer protection against recurrences. Careful interpretation of the results based on lessons learned from previous trials conducted seems crucial. Questions are raised regarding how the results of future studies regarding new strategies researched will be managed and interpreted especially with regard to recurrence management as relevant data must be monitored for at least 30 days after end of treatment.