Targeting Acute Myeloid Leukemia Stem Cells Through Perturbation of Mitochondrial Calcium.

Acute myeloid leukemia stem cells (LSCs) are uniquely reliant on oxidative phosphorylation (OXPHOS) for survival. Moreover, maintenance of OXPHOS is dependent on BCL-2, creating a therapeutic opportunity to target LSCs using the BCL-2 inhibitor venetoclax. While venetoclax-based regimens have shown promising clinical activity, the emergence of drug resistance is prevalent. Thus, in the present study, we investigated how mitochondrial properties may influence venetoclax responsiveness. Our data show that utilization of mitochondrial calcium is fundamentally different between drug-responsive and non-responsive LSCs. By comparison, venetoclax-resistant LSCs demonstrate a more active metabolic (i.e. OXPHOS) status with relatively high levels of calcium. Consequently, we tested genetic and pharmacological approaches to target the mitochondrial calcium uniporter, MCU. We demonstrate that inhibition of calcium uptake reduces OXPHOS and leads to eradication of venetoclax-resistant LSCs. These findings demonstrate a central role for calcium signaling in LSCs and provide an avenue for clinical management of venetoclax resistance.

Targeting Acute Myeloid Leukemia Stem Cells Through Perturbation of Mitochondrial Calcium.

We previously reported that acute myeloid leukemia stem cells (LSCs) are uniquely reliant on oxidative phosphorylation (OXPHOS) for survival. Moreover, maintenance of OXPHOS is dependent on BCL2, creating a therapeutic opportunity to target LSCs using the BCL2 inhibitor drug venetoclax. While venetoclax-based regimens have indeed shown promising clinical activity, the emergence of drug resistance is prevalent. Thus, in the present study, we investigated how mitochondrial properties may influence mechanisms that dictate venetoclax responsiveness. Our data show that utilization of mitochondrial calcium is fundamentally different between drug responsive and non-responsive LSCs. By comparison, venetoclax-resistant LSCs demonstrate a more active metabolic (i.e., OXPHOS) status with relatively high steady-state levels of calcium. Consequently, we tested genetic and pharmacological approaches to target the mitochondrial calcium uniporter, MCU. We demonstrate that inhibition of calcium uptake sharply reduces OXPHOS and leads to eradication of venetoclax-resistant LSCs. These findings demonstrate a central role for calcium signaling in the biology of LSCs and provide a therapeutic avenue for clinical management of venetoclax resistance.

A Novel Type of Monocytic Leukemia Stem Cell Revealed by the Clinical Use of Venetoclax-Based Therapy.

The BCL2 inhibitor venetoclax has recently emerged as an important component of acute myeloid leukemia (AML) therapy. Notably, use of this agent has revealed a previously unrecognized form of pathogenesis characterized by monocytic disease progression. We demonstrate that this form of disease arises from a fundamentally different type of leukemia stem cell (LSC), which we designate as monocytic LSC (m-LSC), that is developmentally and clinically distinct from the more well-described primitive LSC (p-LSC). The m-LSC is distinguished by a unique immunophenotype (CD34-, CD4+, CD11b-, CD14-, CD36-), unique transcriptional state, reliance on purine metabolism, and selective sensitivity to cladribine. Critically, in some instances, m-LSC and p-LSC subtypes can co-reside in the same patient with AML and simultaneously contribute to overall tumor biology. Thus, our findings demonstrate that LSC heterogeneity has direct clinical significance and highlight the need to distinguish and target m-LSCs as a means to improve clinical outcomes with venetoclax-based regimens. SIGNIFICANCE: These studies identify and characterize a new type of human acute myeloid LSC that is responsible for monocytic disease progression in patients with AML treated with venetoclax-based regimens. Our studies describe the phenotype, molecular properties, and drug sensitivities of this unique LSC subclass. This article is featured in Selected Articles from This Issue, p. 1949.

Pancreatic islet cell type-specific transcriptomic changes during pregnancy and postpartum.

Pancreatic ß-cell mass expands during pregnancy and regresses in the postpartum period in conjunction with dynamic metabolic demands on maternal glucose homeostasis. To understand transcriptional changes driving these adaptations in ß-cells and other islet cell types, we performed single-cell RNA sequencing on islets from virgin, late gestation, and early postpartum mice. We identified transcriptional signatures unique to gestation and the postpartum in ß-cells, including induction of the AP-1 transcription factor subunits and other genes involved in the immediate-early response (IEGs). In addition, we found pregnancy and postpartum-induced changes differed within each endocrine cell type, and in endothelial cells and antigen-presenting cells within islets. Together, our data reveal insights into cell type-specific transcriptional changes responsible for adaptations by islet cells to pregnancy and their resolution postpartum.

Vitamin C Status of US Adults Assessed as Part of the National Health and Nutrition Examination Survey Remained Unchanged between 2003-2006 and 2017-2018.

BACKGROUND: We compared serum vitamin C (VIC) status of the adult (≥20 y) US population in the National Health and Nutrition Examination Survey (NHANES) 2017-2018 with combined data from 2003-2004 and 2005-2006. METHODS: VIC was measured using HPLC with electrochemical detection. Mean data were stratified by age, sex, race/Hispanic origin, income, body mass index, dietary intake, supplement use, and smoking status. Prevalence of VIC deficiency (<11.4 µmol/L) was calculated. RESULTS: In NHANES 2017-2018, the mean VIC was 8 µmol/L higher in people ≥60 y compared with those 20-59 y of age, 10 µmol/L lower in men vs women, 8 µmol/L lower in low vs high income, 11 µmol/L lower in obese vs healthy weight, and 15 µmol/L lower in smokers vs nonsmokers. Differences in mean VIC across race/Hispanic origin groups ranged from 2 to 7 µmol/L. Mean VIC was 27 µmol/L higher with vitamin C-containing supplement use and positively associated (Spearman ρ = 0.33; P < 0.0001) with increasing dietary intake. The associations between mean VIC and the investigated covariates were generally consistent and the prevalence of deficiency was not significantly different between survey periods (6.8% vs 7.0%; P = 0.83). However, a few subgroups had double the risk. We found no significant survey differences in mean VIC (51.2 vs 54.0 µmol/L; P = 0.09). CONCLUSIONS: Overall VIC status of the US adult population has remained stable since last assessed in the NHANES 2005-2006 survey. Vitamin C deficiency remained high for those with low dietary intake and who smoke.

Ex Vivo Expansion of Phenotypic and Transcriptomic Chronic Myeloid Leukemia Stem Cells.

Despite decades of research, standard therapies remain ineffective for most leukemias, pushing toward an essential unmet need for targeted drug screens. Moreover, preclinical drug testing is an important consideration for success of clinical trials without affecting non-transformed stem cells. Using the transgenic chronic myeloid leukemia (CML) mouse model, we determine that leukemic stem cells (LSCs) are transcriptionally heterogenous with a preexistent drug-insensitive signature. To test targeting of potentially important pathways, we establish ex vivo expanded LSCs that have long-term engraftment and give rise to multilineage hematopoiesis. Expanded LSCs share transcriptomic signatures with primary LSCs including enrichment in Wnt, JAK-STAT, MAPK, mTOR and transforming growth factor ß signaling pathways. Drug testing on expanded LSCs show that transforming growth factor ß and Wnt inhibitors had significant effects on the viability of LSCs, but not leukemia-exposed healthy HSCs. This platform allows testing of multiple drugs at the same time to identify vulnerabilities of LSCs.

Deciphering Metabolic Adaptability of Leukemic Stem Cells.

Therapeutic targeting of leukemic stem cells is widely studied to control leukemia. An emerging approach gaining popularity is altering metabolism as a potential therapeutic opportunity. Studies have been carried out on hematopoietic and leukemic stem cells to identify vulnerable pathways without impacting the non-transformed, healthy counterparts. While many metabolic studies have been conducted using stem cells, most have been carried out in vitro or on a larger population of progenitor cells due to challenges imposed by the low frequency of stem cells found in vivo. This creates artifacts in the studies carried out, making it difficult to interpret and correlate the findings to stem cells directly. This review discusses the metabolic difference seen between hematopoietic stem cells and leukemic stem cells across different leukemic models. Moreover, we also shed light on the advancements of metabolic techniques and current limitations and areas for additional research of the field to study stem cell metabolism.

Isocitrate dehydrogenase mutations are associated with altered IL-1ß responses in acute myeloid leukemia.

Mutations in isocitrate dehydrogenase 2 (IDH2) have been noted to impact cellular differentiation in addition to DNA and histone methylation. However, little is known about the impact of IDH2 mutations on intracellular signaling. Using an isogenic cell line model, we investigated both differentiation and signaling responses in IDH2 mutant cells and show augmented responses to inflammatory immune ligands. Using phospho-specific flow and mass cytometry, we demonstrate IDH2 mutant cells were significantly more sensitive to IL-1ß at multiple downstream readouts. Further, bulk RNA sequencing confirmed increases in cytokine-related signaling pathways and NF-κB target genes. Single-cell RNA sequencing of unstimulated and stimulated cells confirmed altered IL-1ß transcriptional responses in the IDH2 mutant cells. Targeted inhibition of the IKK complex reduced IL-1ß responses and induced cell death in primary IDH-mutated leukemia samples. Together, these results confirm altered IL-1ß signaling in IDH2 mutant cells and identify this pathway as a potential therapeutic target.

Does Motor Control Exercise Restore Normal Morphology of Lumbar Multifidus Muscle in People with Low Back Pain? - A Systematic Review.

Aberrant morphological changes in lumbar multifidus muscle (LMM) are prevalent among patients with low back pain (LBP). Motor control exercise (MCE) aims to improve the activation and coordination of deep trunk muscles (eg, LMM), which may restore normal LMM morphology and reduce LBP. However, its effects on LMM morphology have not been summarized. This review aimed to summarize evidence regarding the (1) effectiveness of MCE in altering LMM morphometry and decreasing LBP; and (2) relations between post-MCE changes in LMM morphometry and LBP/LBP-related disability. Cumulative Index to Nursing and Allied Health Literature, MEDLINE, Cochrane Central Register of Controlled Trials, the Physiotherapy Evidence Database, EMBASE and SPORTDiscus were searched from inception to 30 September 2020 to identify relevant randomized controlled trials. Two reviewers independently screened articles, extracted data, and evaluated risk of bias and quality of evidence. Four hundred and fifty-one participants across 9 trials were included in the review. Very low-quality evidence supported that 36 sessions of MCE were better than general physiotherapy in causing minimal detectable increases in LMM cross-sectional areas of patients with chronic LBP. Very low- to low-quality evidence suggested that MCE was similar to other interventions in increasing resting LMM thickness in patients with chronic LBP. Low-quality evidence substantiated that MCE was significantly better than McKenzie exercise or analgesics in increasing contracted LMM thickness in patients with chronic LBP. Low-quality evidence corroborated that MCE was not significantly better than other exercises in treating people with acute/chronic LBP. Low-quality evidence suggested no relation between post-MCE changes in LMM morphometry and LBP/LBP-related disability. Collectively, while MCE may increase LMM dimensions in patients with chronic LBP, such changes may be unrelated to clinical outcomes. This raises the question regarding the role of LMM in LBP development/progression.

Metabolic alterations mediated by STAT3 promotes drug persistence in CML.

Leukemic stem cells (LSCs) can acquire non-mutational resistance following drug treatment leading to therapeutic failure and relapse. However, oncogene-independent mechanisms of drug persistence in LSCs are incompletely understood, which is the primary focus of this study. We integrated proteomics, transcriptomics, and metabolomics to determine the contribution of STAT3 in promoting metabolic changes in tyrosine kinase inhibitor (TKI) persistent chronic myeloid leukemia (CML) cells. Proteomic and transcriptional differences in TKI persistent CML cells revealed BCR-ABL-independent STAT3 activation in these cells. While knockout of STAT3 inhibited the CML cells from developing drug-persistence, inhibition of STAT3 using a small molecule inhibitor sensitized the persistent CML cells to TKI treatment. Interestingly, given the role of phosphorylated STAT3 as a transcription factor, it localized uniquely to genes regulating metabolic pathways in the TKI-persistent CML stem and progenitor cells. Subsequently, we observed that STAT3 dysregulated mitochondrial metabolism forcing the TKI-persistent CML cells to depend on glycolysis, unlike TKI-sensitive CML cells, which are more reliant on oxidative phosphorylation. Finally, targeting pyruvate kinase M2, a rate-limiting glycolytic enzyme, specifically eradicated the TKI-persistent CML cells. By exploring the role of STAT3 in altering metabolism, we provide critical insight into identifying potential therapeutic targets for eliminating TKI-persistent LSCs.

E-cadherin is regulated by GATA-2 and marks the early commitment of mouse hematopoietic progenitors to the basophil and mast cell fates.

E-cadherin is a calcium-dependent cell-cell adhesion molecule extensively studied for its involvement in tissue formation, epithelial cell behavior, and suppression of cancer. However, E-cadherin expression in the hematopoietic system has not been fully elucidated. Combining single-cell RNA-sequencing analyses and immunophenotyping, we revealed that progenitors expressing high levels of E-cadherin and contained within the granulocyte-monocyte progenitors (GMPs) fraction have an enriched capacity to differentiate into basophils and mast cells. We detected E-cadherin expression on committed progenitors before the expression of other reported markers of these lineages. We named such progenitors pro-BMPs (pro-basophil and mast cell progenitors). Using RNA sequencing, we observed transcriptional priming of pro-BMPs to the basophil and mast cell lineages. We also showed that GATA-2 directly regulates E-cadherin expression in the basophil and mast cell lineages, thus providing a mechanistic connection between the expression of this cell surface marker and the basophil and mast cell fate specification.

Bone marrow Tregs mediate stromal cell function and support hematopoiesis via IL-10.

The nonimmune roles of Tregs have been described in various tissues, including the BM. In this study, we comprehensively phenotyped marrow Tregs, elucidating their key features and tissue-specific functions. We show that marrow Tregs are migratory and home back to the marrow. For trafficking, marrow Tregs use S1P gradients, and disruption of this axis allows for specific targeting of the marrow Treg pool. Following Treg depletion, the function and phenotype of both mesenchymal stromal cells (MSCs) and hematopoietic stem cells (HSCs) was impaired. Transplantation also revealed that a Treg-depleted niche has a reduced capacity to support hematopoiesis. Finally, we found that marrow Tregs are high producers of IL-10 and that Treg-secreted IL-10 has direct effects on MSC function. This is the first report to our knowledge revealing that Treg-secreted IL-10 is necessary for stromal cell maintenance, and our work outlines an alternative mechanism by which this cytokine regulates hematopoiesis.

Brachytherapy for Oral Cavity Cancers in the Era of Intensity-Modulated Radiotherapy: Save it or Shelve it.

Head and neck cancer treatment includes a multidisciplinary approach involving all specialties. Surgery and radiotherapy are equally effective in controlling small tumors. Intensity-modulated radiotherapy (IMRT) and interstitial brachytherapy (ISBT) play an important role in the treatment of head and neck cancers. Both are proved to be highly conformal techniques of radiotherapy. Our aim is to compare dosimetric aspects of ISBT alone, IMRT alone, and IMRT combined with ISBT in early stage node negative oral cavity cancer. Ten cases of histopathologically proven early stage node negative oral cavity cancer were treated with external beam therapy followed by interstitial brachytherapy boost or ISBT alone. All these patients had undergone computerized tomography (CT) planning for brachytherapy. Retrospectively, these images were utilized, and three sets of plans were done for each patient's CT image set. Group A was IMRT alone plans, groups B had combined IMRT with ISBT boost, and group C was ISBT alone plans. Dosimetric details such as target coverage, dose to critical organs, and conformity index were compared between the three sets of plans. The mean values of the doses to the critical organs with IMRT alone and IMRT with ISBT boost were brainstem 10.40 Gy and 9.20 Gy, spinal cord 19.20 Gy and 16.10 Gy, mandible 62.99 Gy and 66.50 Gy, and I/L and C/L parotids were 6.03 Gy and 5.50 Gy and 5.70 Gy and 5.10 Gy where as in ISBT alone plans mean values were brainstem 1.30 Gy, spinal cord 1.40 Gy, mandible 36.50 Gy, I/L, and C/L parotids were 1.60 Gy and 1.00 Gy. Conformity index (CI) between IMRT and ISBT plans were 0.8580 and 0.7140 respectively. With comparable CI values, doses to critical organs appear to be in favor of ISBT plans as opposed to IMRT, and this was found to be statistically significant. Brachytherapy shows a dosimetric advantage over IMRT in this setting and could be translated to a benefit in terms of toxicities, organ preservation, and cosmesis in the actual clinical scenario. However, whether this would translate to significant benefit in terms of clinical outcome needs to be still verified.

Single-Cell RNA-Seq Mapping of Human Thymopoiesis Reveals Lineage Specification Trajectories and a Commitment Spectrum in T Cell Development.

The challenges in recapitulating in vivo human T cell development in laboratory models have posed a barrier to understanding human thymopoiesis. Here, we used single-cell RNA sequencing (sRNA-seq) to interrogate the rare CD34+ progenitor and the more differentiated CD34- fractions in the human postnatal thymus. CD34+ thymic progenitors were comprised of a spectrum of specification and commitment states characterized by multilineage priming followed by gradual T cell commitment. The earliest progenitors in the differentiation trajectory were CD7- and expressed a stem-cell-like transcriptional profile, but had also initiated T cell priming. Clustering analysis identified a CD34+ subpopulation primed for the plasmacytoid dendritic lineage, suggesting an intrathymic dendritic specification pathway. CD2 expression defined T cell commitment stages where loss of B cell potential preceded that of myeloid potential. These datasets delineate gene expression profiles spanning key differentiation events in human thymopoiesis and provide a resource for the further study of human T cell development.

Isolation of DNA-free RNA from human bone marrow mononuclear cells: comparison of laboratory methods.

RNA quality (purity and integrity) and quantity are of critical importance to ensure reliable gene expression analysis, reproducibility of RNA sequencing and microarray data and validation by RT-PCR. Currently available methods for isolating RNA either are labor intensive (requiring the use of toxic organic solvents and separate DNase treatment) or require automation (with extensive setup and startup costs). To optimize both the quality and quantity of RNA from bone marrow, we recommend stabilization and storage of bone marrow mononuclear cells in RNAprotect® Cell Reagent, followed by extraction using the RNeasy® Protect Cell Mini Kit (Qiagen, Hilden, Germany). This method achieves optimal quantity and high-quality RNA for sequencing and RT-PCR while remaining efficient and cost effective.

Growth hormone (GH) receptor (GHR)-specific inhibition of GH-Induced signaling by soluble IGF-1 receptor (sol IGF-1R).

Human growth hormone (GH) binds and activates GH receptor (GHR) and prolactin (PRL) receptor (PRLR). LNCaP human prostate cancer cells express only GHR. A soluble fragment of IGF-1 receptor (IGF-1R) extracellular domain (sol IGF-1R) interacts with GHR and blocks GH signaling. We now explore sol IGF-1R's specificity for inhibiting GH signaling via GHR vs. PRLR and test GHR and PRLR extracellular domain inhibition determinants. Although T47D human breast cancer cells express GHR and PRLR, GH signaling is largely PRLR-mediated. In T47D, sol IGF-1R inhibited neither GH- nor PRL-induced STAT5 activation. However, sol IGF-1R inhibited GH-induced STAT5 activation in T47D-shPRLR cells, which harbor reduced PRLR. In MIN6 mouse ß-cells, bovine GH (bGH) activates mouse GHR, not PRLR, while human GH activates mouse GHR and PRLR. In MIN6, sol IGF-1R inhibited bGH-induced STAT5 activation, but partially inhibited human GH-induced STAT5 activation. These findings suggest sol IGF-1R's inhibition is GHR-specific. Using a cellular reconstitution system, we compared effects of sol IGF-1R on signaling through GHR, PRLR, or chimeras in which extracellular subdomains 2 (S2) of the receptors were swapped. Sol IGF-1R inhibited GH-induced STAT5 activation in GHR-expressing, not PRLR-expressing cells, consistent with GHR specificity of sol IGF-1R. Interestingly, we found that GHR S2 (which harbors the GHR-GHR dimer interface) was required, but not sufficient for sol IGF-1R inhibition of GHR signaling. These results suggest sol IGF-1R specifically inhibits GH-induced GHR-mediated signaling, possibly through interaction with GHR S1 and S2 domains. Our findings have implications for GH antagonist development.

Multifunctionalization of Poly(vinylidene fluoride)/Reactive Copolymer Blend Membranes for Broad Spectrum Applications.

Simultaneous immobilization and cross-linking of antifouling/low toxic polymers, e.g., poly(ethylenimine) (PEI), dextran (Dex), agarose (Agr), poly(ethylene glycol) (PEG), PEI-Dex, and PEI-PEG conjugates, and stimuli-responsive copolymers on a porous membrane surface in mild reaction conditions is desirable for the enhancement of hydrophilicity, antifouling character, cytocompatibility, and inducing stimuli-responsive behavior. Grafting to technique is required since the precursors of most of these macromolecules are not amenable to surface-initiated polymerization. In this work, we report a versatile process for the simultaneous immobilization and cross-linking of a library of macromolecules on and into the blend membrane (PVDF-blend) of poly(vinylidene fluoride) and poly(methyl methacrylate)-co-poly(chloromethylstyrene). Sequential nucleophilic substitution reaction between activated halide moieties of the copolymer and amine groups of different macromolecules readily provided series of modified membranes. These membranes exhibited antifouling property superior to that of the unmodified membrane. The effectiveness of this technique has been demonstrated by the immobilization of pH or both pH- and temperature-responsive copolymer on PVDF-blend membrane for responsive separation of poly(ethylene oxide) and bovine serum albumin. Silver nanoparticles were also anchored on the select modified membranes surfaces for the enhancement of antibiofouling property. Our approach is useful to obtain verities of functional membranes and selection of membrane for a particular application.

Outcome of endodontic surgery: a meta-analysis of the literature--Part 2: Comparison of endodontic microsurgical techniques with and without the use of higher magnification.

INTRODUCTION: The aim of this study was to investigate the outcome of root-end surgery. It identifies the effect of the surgical operating microscope or the endoscope on the prognosis of endodontic surgery. The specific outcomes of contemporary root-end surgery techniques with microinstruments but only loupes or no visualization aids (contemporary root-end surgery [CRS]) were compared with endodontic microsurgery using the same instruments and materials but with high-power magnification as provided by the surgical operating microscope or the endoscope (endodontic microsurgery [EMS]). The probabilities of success for a comparison of the 2 techniques were determined by means of a meta-analysis and systematic review of the literature. The influence of the tooth type on the outcome was investigated. METHODS: A comprehensive literature search for longitudinal studies on the outcome of root-end surgery was conducted. Three electronic databases (ie, Medline, Embase, and PubMed) were searched to identify human studies from 1966 up to October 2009 in 5 different languages (ie, English, French, German, Italian, and Spanish). Review articles and relevant articles were searched for cross-references. In addition, 5 dental and medical journals (ie, Journal of Endodontics, International Endodontic Journal, Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontics, Journal of Oral and Maxillofacial Surgery, and International Journal of Oral and Maxillofacial Surgery) dating back to 1975 were hand searched. Following predefined inclusion and exclusion criteria, all articles were screened by 3 independent reviewers (S.B.S., M.R.K., and F.C.S.). Relevant articles were obtained in full-text form, and raw data were extracted independently by each reviewer. After agreement among the reviewers, articles that qualified were assigned to group CRS. Articles belonging to group EMS had already been obtained for part 1 of this meta-analysis. Weighted pooled success rates and a relative risk assessment between CRS and EMS overall as well as for molars, premolars, and anteriors were calculated. A random-effects model was used for a comparison between the groups. RESULTS: One hundred one articles were identified and obtained for final analysis. In total, 14 studies qualified according to the inclusion and exclusion criteria, 2 being represented in both groups (7 for CRS [n = 610] and 9 for EMS [n = 699]). Weighted pooled success rates calculated from extracted raw data showed an 88% positive outcome for CRS (95% confidence interval, 0.8455-0.9164) and 94% for EMS (95% confidence interval, 0.8889-0.9816). This difference was statistically significant (P < .0005). Relative risk ratio analysis showed that the probability of success for EMS was 1.07 times the probability of success for CRS. Seven studies provided information on the individual tooth type (4 for CRS [n = 457] and 3 for EMS [n = 222]). The difference in probability of success between the groups was statistically significant for molars (n = 193, P = .011). No significant difference was found for the premolar or anterior group (premolar [n = 169], P = .404; anterior [n = 277], P = .715). CONCLUSIONS: The probability for success for EMS proved to be significantly greater than the probability for success for CRS, providing best available evidence on the influence of high-power magnification rendered by the dental operating microscope or the endoscope. Large-scale randomized clinical trials for statistically valid conclusions for current endodontic questions are needed to make informed decisions for clinical practice.

Outcome of endodontic surgery: a meta-analysis of the literature--part 1: Comparison of traditional root-end surgery and endodontic microsurgery.

INTRODUCTION: The aim of this study was to investigate the outcome of root-end surgery. The specific outcome of traditional root-end surgery (TRS) versus endodontic microsurgery (EMS) and the probability of success for comparison of the 2 techniques were determined by means of meta-analysis and systematic review of the literature. METHODS: An intensive search of the literature was conducted to identify longitudinal studies evaluating the outcome of root-end surgery. Three electronic databases (Medline, Embase, and PubMed) were searched to identify human studies from 1966 to October 2009 in 5 different languages (English, French, German, Italian, and Spanish). Relevant articles and review papers were searched for cross-references. Five pertinent journals (Journal of Endodontics, International Endodontic Journal, Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontics, Journal of Oral and Maxillofacial Surgery, International Journal of Oral and Maxillofacial Surgery) were individually searched back to 1975. Three independent reviewers (S.S., M.K., and F.S.) assessed the abstracts of all articles that were found according to predefined inclusion and exclusion criteria. Relevant articles were acquired in full-text form, and raw data were extracted independently by each reviewer. Qualifying papers were assigned to group TRS or group EMS. Weighted pooled success rates and relative risk assessment between TRS and EMS were calculated. A comparison between the groups was made by using a random effects model. RESULTS: Ninety-eight articles were identified and obtained for final analysis. In total, 21 studies qualified (12 for TRS [n = 925] and 9 for EMS [n = 699]) according to the inclusion and exclusion criteria. Weighted pooled success rates calculated from extracted raw data showed 59% positive outcome for TRS (95% confidence interval, 0.55-0.6308) and 94% for EMS (95% confidence interval, 0.8889-0.9816). This difference was statistically significant (P < .0005). The relative risk ratio showed that the probability of success for EMS was 1.58 times the probability of success for TRS. CONCLUSIONS: The use of microsurgical techniques is superior in achieving predictably high success rates for root-end surgery when compared with traditional techniques.