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Haematopoietic stem cell (HSC) gene therapy (GT) may provide lifelong reconstitution of the haematopoietic system with gene-corrected cells 1 . However, the effects of underlying genetic diseases, replication stress and ageing on haematopoietic reconstitution and lineage specification remain unclear. In this study, we analysed haematopoietic reconstitution in 53 patients treated with lentiviral-HSC-GT for diverse conditions such as metachromatic leukodystrophy 2,3 (MLD), Wiskott-Aldrich syndrome 4,5 (WAS) and β-thalassaemia 6 (β-Thal) over a follow-up period of up to 8 years, using vector integration sites as markers of clonal identity. We found that long-term haematopoietic reconstitution was supported by 770 to 35,000 active HSCs. Whereas 50% of transplanted clones demonstrated multi-lineage potential across all conditions, the remaining clones showed a disease-specific preferential lineage output and long-term commitment: myeloid for MLD, lymphoid for WAS and erythroid for β-Thal, particularly in adult patients. Our results indicate that HSC clonogenic activity, lineage output, long-term lineage commitment and rates of somatic mutations are influenced by the underlying disease, patient age at the time of therapy, the extent of genetic defect correction and the haematopoietic stress imposed by the inherited disease. This suggests that HSCs adapt to the pathological condition during haematopoietic reconstitution., Competing Interests: Competing interests: The San Raffaele Telethon Institute for GT (SR-Tiget) is a joint venture between the Telethon Foundation and Ospedale San Raffaele. Lentiviral vector-based gene therapy for metachromatic leukodystrophy (MLD), developed at SR-Tiget, was licensed to Orchard Therapeutics in 2018. Lentiviral vector-based gene therapy for Wiskott–Aldrich (WAS) syndrome was developed by Fondazione Telethon. Lentiviral vector-based gene therapy for β-thalassemia was developed at SR-Tiget. Gene therapy for MLD is approved in the EU (Libmeldy) and in the US (Lenmeldy). A.A. was the principal investigator of the pilot and pivotal SR-Tiget clinical trial of GT for MLD, WAS and β-Thal. The other authors declare no competing interests., (© 2024. The Author(s).)

Base and prime editors (BEs and PEs) may provide more precise genetic engineering than nuclease-based approaches because they bypass the dependence on DNA double-strand breaks. However, little is known about their cellular responses and genotoxicity. Here, we compared state-of-the-art BEs and PEs and Cas9 in human hematopoietic stem and progenitor cells with respect to editing efficiency, cytotoxicity, transcriptomic changes and on-target and genome-wide genotoxicity. BEs and PEs induced detrimental transcriptional responses that reduced editing efficiency and hematopoietic repopulation in xenotransplants and also generated DNA double-strand breaks and genotoxic byproducts, including deletions and translocations, at a lower frequency than Cas9. These effects were strongest for cytidine BEs due to suboptimal inhibition of base excision repair and were mitigated by tailoring delivery timing and editor expression through optimized mRNA design. However, BEs altered the mutational landscape of hematopoietic stem and progenitor cells across the genome by increasing the load and relative proportions of nucleotide variants. These findings raise concerns about the genotoxicity of BEs and PEs and warrant further investigation in view of their clinical application., (© 2023. The Author(s).)

Mucopolysaccharidosis type I Hurler (MPSIH) is characterized by severe and progressive skeletal dysplasia that is not fully addressed by allogeneic hematopoietic stem cell transplantation (HSCT). Autologous hematopoietic stem progenitor cell-gene therapy (HSPC-GT) provides superior metabolic correction in patients with MPSIH compared with HSCT; however, its ability to affect skeletal manifestations is unknown. Eight patients with MPSIH (mean age at treatment: 1.9 years) received lentiviral-based HSPC-GT in a phase 1/2 clinical trial (NCT03488394). Clinical (growth, measures of kyphosis and genu velgum), functional (motor function, joint range of motion), and radiological [acetabular index (AI), migration percentage (MP) in hip x-rays and MRIs and spine MRI score] parameters of skeletal dysplasia were evaluated at baseline and multiple time points up to 4 years after treatment. Specific skeletal measures were retrospectively compared with an external cohort of HSCT-treated patients. At a median follow-up of 3.78 years after HSPC-GT, all patients treated with HSPC-GT exhibited longitudinal growth within WHO reference ranges and a median height gain greater than that observed in patients treated with HSCT after 3-year follow-up. Patients receiving HSPC-GT experienced complete and earlier normalization of joint mobility compared with patients treated with HSCT. Mean AI and MP showed progressive decreases after HSPC-GT, suggesting a reduction in acetabular dysplasia. Typical spine alterations measured through a spine MRI score stabilized after HSPC-GT. Clinical, functional, and radiological measures suggested an early beneficial effect of HSPC-GT on MPSIH-typical skeletal features. Longer follow-up is needed to draw definitive conclusions on HSPC-GT's impact on MPSIH skeletal dysplasia.

Recombination activating genes ( RAGs ) are tightly regulated during lymphoid differentiation, and their mutations cause a spectrum of severe immunological disorders. Hematopoietic stem and progenitor cell (HSPC) transplantation is the treatment of choice but is limited by donor availability and toxicity. To overcome these issues, we developed gene editing strategies targeting a corrective sequence into the human RAG1 gene by homology-directed repair (HDR) and validated them by tailored two-dimensional, three-dimensional, and in vivo xenotransplant platforms to assess rescue of expression and function. Whereas integration into intron 1 of RAG1 achieved suboptimal correction, in-frame insertion into exon 2 drove physiologic human RAG1 expression and activity, allowing disruption of the dominant-negative effects of unrepaired hypomorphic alleles. Enhanced HDR-mediated gene editing enabled the correction of human RAG1 in HSPCs from patients with hypomorphic RAG1 mutations to overcome T and B cell differentiation blocks. Gene correction efficiency exceeded the minimal proportion of functional HSPCs required to rescue immunodeficiency in Rag1 -/- mice, supporting the clinical translation of HSPC gene editing for the treatment of RAG1 deficiency.

Hyper IgM1 is an X-linked combined immunodeficiency caused by CD40LG mutations, potentially treatable with CD4 + T-cell gene editing with Cas9 and a "one-size-fits-most" corrective template. Contrary to established gene therapies, there is limited data on the genomic alterations following long-range gene editing, and no consensus on the relevant assays. We developed drop-off digital PCR assays for unbiased detection of large on-target deletions and found them at high frequency upon editing. Large deletions were also common upon editing different loci and cell types and using alternative Cas9 and template delivery methods. In CD40LG edited T cells, on-target deletions were counter-selected in culture and further purged by enrichment for edited cells using a selector coupled to gene correction. We then validated the sensitivity of optical genome mapping for unbiased detection of genome wide rearrangements and uncovered on-target trapping of one or more vector copies, which do not compromise functionality, upon editing using an integrase defective lentiviral donor template. No other recurring events were detected. Edited patient cells showed faithful reconstitution of CD40LG regulated expression and function with a satisfactory safety profile. Large deletions and donor template integrations should be anticipated and accounted for when designing and testing similar gene editing strategies., (© 2023 The Authors. Published under the terms of the CC BY NC ND 4.0 license.)

Introduction: In haematopoietic stem cell transplantation (HSCT), haematopoietic stem cells (HSCs) from a healthy donor replace the patient's ones. Ex vivo HSC gene therapy (HSC-GT) is a form of HSCT in which HSCs, usually from an autologous source, are genetically modified before infusion, to generate a progeny of gene-modified cells. In HSCT and HSC-GT, chemotherapy is administered before infusion to free space in the bone marrow (BM) niche, which is required for the engraftment of infused cells. Here, we review alternative chemotherapy-free approaches to niche voidance that could replace conventional regimens and alleviate the morbidity of the procedure., Sources of Data: Literature was reviewed from PubMed-listed peer-reviewed articles. No new data are presented in this article., Areas of Agreement: Chemotherapy exerts short and long-term toxicity to haematopoietic and non-haematopoietic organs. Whenever chemotherapy is solely used to allow engraftment of donor HSCs, rather than eliminating malignant cells, as in the case of HSC-GT for inborn genetic diseases, non-genotoxic approaches sparing off-target tissues are highly desirable., Areas of Controversy: In principle, HSCs can be temporarily moved from the BM niches using mobilizing drugs or selectively cleared with targeted antibodies or immunotoxins to make space for the infused cells. However, translation of these principles into clinically relevant settings is only at the beginning, and whether therapeutically meaningful levels of chimerism can be safely established with these approaches remains to be determined., Growing Points: In pre-clinical models, mobilization of HSCs from the niche can be tailored to accommodate the exchange and engraftment of infused cells. Infused cells can be further endowed with a transient engraftment advantage., Areas Timely for Developing Research: Inter-individual efficiency and kinetics of HSC mobilization need to be carefully assessed. Investigations in large animal models of emerging non-genotoxic approaches will further strengthen the rationale and encourage application to the treatment of selected diseases., (© The Author(s) 2023. Published by Oxford University Press.)

Hyper-IgM1 is a rare X-linked combined immunodeficiency caused by mutations in the CD40 ligand ( CD40LG ) gene with a median survival of 25 years, potentially treatable with in situ CD4+ T cell gene editing with Cas9 and a one-size-fits-most corrective donor template. Here, starting from our research-grade editing protocol, we pursued the development of a good manufacturing practice (GMP)-compliant, scalable process that allows for correction, selection and expansion of edited cells, using an integrase defective lentiviral vector as donor template. After systematic optimization of reagents and conditions we proved maintenance of stem and central memory phenotypes and expression and function of CD40LG in edited healthy donor and patient cells recapitulating the physiological CD40LG regulation. We then documented the preserved fitness of edited cells by xenotransplantation into immunodeficient mice. Finally, we transitioned to large-scale manufacturing, and developed a panel of quality control assays. Overall, our GMP-compliant process takes long-range gene editing one step closer to clinical application with a reassuring safety profile., Competing Interests: L.N., C.A., M.R., V.V., A.V., S.F., S.P., D.C., and A.J. are inventors of patent applications owned by Ospedale San Raffaele S.r.l. and Fondazione Telethon ETS, including one patent application on CD40LG gene editing. L.N. is founder, quota holder, and consultant of GeneSpire S.r.l., (© 2023 The Authors.)

Vaccination with Bacillus Calmette-Guérin (BCG) can be harmful to patients with combined primary immunodeficiencies. We report the outcome of BCG vaccination in a series of twelve patients affected by adenosine deaminase deficiency (ADA-SCID). BCG vaccination resulted in a very high incidence of complications due to uncontrolled replication of the mycobacterium. All patients who developed BCG-related disease were treated successfully and remained free from recurrence of disease. We recommend the prompt initiation of enzyme replacement therapy and secondary prophylaxis to reduce the risk of BCG-related complications in ADA-SCID patients.

Aims: Wolfram Syndrome Spectrum Disorder (WFS1-SD), in its "classic" form, is a rare autosomal recessive disease with poor prognosis and wide phenotypic spectrum. Insulin dependent diabetes mellitus (DM), optic atrophy (OA) diabetes insipidus (DI) and sensorineural deafness (D) are the main features of WFS1-SD. Gonadal dysfunction (GD) has been described mainly in adults with variable prevalence and referred to as a minor clinical feature. This is the first case series investigating gonadal function in a small cohort of paediatric patients affected by WFS1-SD., Methods: Gonadal function was investigated in eight patients (3 male and 5 female) between 3 and 16 years of age. Seven patients have been diagnosed with classic WFS1-SD and one with non-classic WFS1-SD. Gonadotropin and sex hormone levels were monitored, as well as markers of gonadal reserve (inhibin-B and anti-Mullerian hormone). Pubertal progression was assessed according to Tanner staging., Results: Primary hypogonadism was diagnosed in 50% of patients (n=4), more specifically 67% (n=2) of males and 40% of females (n=2). Pubertal delay was observed in one female patient. These data confirm that gonadal dysfunction may be a frequent and underdiagnosed clinical feature in WFS1-SD., Conclusions: GD may represent a frequent and earlier than previously described feature in WFS1-SD with repercussions on morbidity and quality of life. Consequently, we suggest that GD should be included amongst clinical diagnostic criteria for WFS1-SD, as has already been proposed for urinary dysfunction. Considering the heterogeneous and elusive presentation of WFS1-SD, this clinical feature may assist in an earlier diagnosis and timely follow-up and care of treatable associated diseases (i.e. insulin and sex hormone replacement) in these young patients., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Frontino, Di Tonno, Stancampiano, Arrigoni, Rigamonti, Morotti, Canarutto, Bonfanti, Russo, Barera and Piemonti.)

Long-range gene editing by homology-directed repair (HDR) in hematopoietic stem/progenitor cells (HSPCs) often relies on viral transduction with recombinant adeno-associated viral vector (AAV) for template delivery. Here, we uncover unexpected load and prolonged persistence of AAV genomes and their fragments, which trigger sustained p53-mediated DNA damage response (DDR) upon recruiting the MRE11-RAD50-NBS1 (MRN) complex on the AAV inverted terminal repeats (ITRs). Accrual of viral DNA in cell-cycle-arrested HSPCs led to its frequent integration, predominantly in the form of transcriptionally competent ITRs, at nuclease on- and off-target sites. Optimized delivery of integrase-defective lentiviral vector (IDLV) induced lower DNA load and less persistent DDR, improving clonogenic capacity and editing efficiency in long-term repopulating HSPCs. Because insertions of viral DNA fragments are less frequent with IDLV, its choice for template delivery mitigates the adverse impact and genotoxic burden of HDR editing and should facilitate its clinical translation in HSPC gene therapy., Competing Interests: Declaration of interests L.N., A.K.-R., A.V., M.C.C., S.F., and A.J. are inventors of patents on gene editing owned and managed by the San Raffaele Scientific Institute and Telethon Foundation. L.N. is founder, quota holder, and consultant of GeneSpire, a startup company aiming to develop ex vivo gene editing and exploiting IDLV., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

Hematopoietic stem/progenitor cell gene therapy (HSPC-GT) is proving successful to treat several genetic diseases. HSPCs are mobilized, harvested, genetically corrected ex vivo, and infused, after the administration of toxic myeloablative conditioning to deplete the bone marrow (BM) for the modified cells. We show that mobilizers create an opportunity for seamless engraftment of exogenous cells, which effectively outcompete those mobilized, to repopulate the depleted BM. The competitive advantage results from the rescue during ex vivo culture of a detrimental impact of mobilization on HSPCs and can be further enhanced by the transient overexpression of engraftment effectors exploiting optimized mRNA-based delivery. We show the therapeutic efficacy in a mouse model of hyper IgM syndrome and further developed it in human hematochimeric mice, showing its applicability and versatility when coupled with gene transfer and editing strategies. Overall, our findings provide a potentially valuable strategy paving the way to broader and safer use of HSPC-GT., Competing Interests: Declaration of interests L.N. is the inventor of patents on the applications of gene editing in HSPCs, owned and managed by the San Raffaele Scientific Institute and the Telethon Foundation, including the improved gene editing filed by L.N., S.F., A.J., and M.F., the increasing engraftment by HSPCs filed by L.N., C.L. and M.M. and the mobilization-based HSCT filed by L.N. and A.O.-J. L.N. is a co-founder and quota holder of GeneSpire, a startup company aiming to develop ex vivo gene editing in genetic diseases., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: Gastric emptying time is one of limiting factors that determines the pharmacokinetic properties of drugs administered by mouth. Despite the high prevalence of obesity worldwide, modifications in gastric emptying time have not been systematically addressed in this set of patients. The current analysis aims to quantitatively address obesity-related changes in gastric emptying time of solids, semisolids, and liquids compared with lean individuals, highlighting the relevant pharmacokinetic implications of oral drug absorption in patients with obesity., Methods: We searched the Cochrane Library, PubMed, Web of Science, and Embase for all relevant articles published until November 1, 2020. Differences in gastrointestinal variables in relation to gastric emptying between obese and lean individuals were quantified by weighted mean difference (WMD) and ratio of means (RoM). Robustness of the analyses was evaluated by subgroup analysis and publication bias test., Findings: A total of 17 studies with 906 participants were included. The gastric half-emptying time of solids (WMD, -10.4 minutes; P = 0.001; RoM, 0.90; P = 0.01) and liquids (WMD, -6.14 minutes; P < 0.001; RoM, 0.83, P = 0.03) was significantly shorter in individuals with obesity compared with lean individuals. These findings were confirmed by the subgroup analyses and publication bias tests., Implications: Our pooled analysis systemically quantifies the differences in gastric half-emptying time between individuals with obesity and lean individuals, facilitating better understanding and prediction of drug absorption in individuals with obesity through physiologically based pharmacokinetic approaches. Obesity is associated with a faster transit of both solids and liquids through the stomach., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Hematopoietic stem and progenitor cell (HSPC)-based gene therapy (GT) requires the collection of a large number of cells. While bone marrow (BM) is the most common source of HSPCs in pediatric donors, the collection of autologous peripheral blood stem cells (PBSCs) is an attractive alternative for GT. We present safety and efficacy data of a 10-year cohort of 45 pediatric patients who underwent PBSC collection for backup and/or purification of CD34 + cells for ex vivo gene transfer. Median age was 3.7 years and median weight 15.8 kg. After mobilization with lenograstim/plerixafor (n = 41) or lenograstim alone (n = 4) and 1-3 cycles of leukapheresis, median collection was 37 × 10 6 CD34 + cells/kg. The procedures were well tolerated. Patients who collected ≥7 and ≥13 × 10 6 CD34 + cells/kg in the first cycle had pre-apheresis circulating counts of at ≥42 and ≥86 CD34 + cells/μL, respectively. Weight-adjusted CD34 + cell yield was positively correlated with peripheral CD34 + cell counts and influenced by female gender, disease, and drug dosage. All patients received a GT product above the minimum target, ranging from 4 to 30.9 × 10 6 CD34 + cells/kg. Pediatric PBSC collection compares well to BM harvest in terms of CD34 + cell yields for the purpose of GT, with a favorable safety profile., Competing Interests: SR-TIGET is a joint venture between Fondazione Telethon and OSR. Gene therapies for ADA-SCID, WAS, MLD, β-thalassemia, and MPSIH developed at SR-TIGET were licensed to Orchard Therapeutics (OTL) in 2018 and 2019. A.A. is the principal investigator (PI) of the above clinical trials. M.E.B. is the current PI of the MPSIH clinical trial., (© 2021.)

In the field of hematology, gene therapies based on integrating vectors have reached outstanding results for a number of human diseases. With the advent of novel programmable nucleases, such as CRISPR/Cas9, it has been possible to expand the applications of gene therapy beyond semi-random gene addition to site-specific modification of the genome, holding the promise for safer genetic manipulation. Here we review the state of the art of ex vivo gene editing with programmable nucleases in human hematopoietic stem and progenitor cells (HSPCs). We highlight the potential advantages and the current challenges toward safe and effective clinical translation of gene editing for the treatment of hematological diseases., Competing Interests: SF, VV, AJac, MC, and PG are inventors of patent applications on gene editing in HSPCs and cell selection owned and managed by the San Raffaele Scientific Institute and the Telethon Foundation. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Ferrari, Vavassori, Canarutto, Jacob, Castiello, Javed and Genovese.)

Collection of an adequate amount of autologous haematopoietic stem progenitor cells (HSPC) is required for ex vivo manipulation and successful engraftment for certain inherited disorders. Fifty-seven paediatric patients (age 0.5-11.4 years) underwent a bone marrow harvest for the purpose of HSPC gene therapy (GT), including adenosine deaminase-severe combined immunodeficiency (ADA-SCID), Wiskott-Aldrich syndrome (WAS) and metachromatic leukodystrophy (MLD) patients. Total nucleated cells and the percentage and absolute counts of CD34+ cells were calculated at defined steps of the procedure (harvest, CD34+ cell purification, transduction with the gene transfer vector and infusion of the medicinal product). A minimum CD34+ cell dose for infusion was 2 × 10 6 /kg, with an optimal target at 5-10 × 10 6 /kg. Median volume of bone marrow harvested was 34.2 ml/kg (range 14.2-56.6). The number of CD34+ cells collected correlated inversely with weight and age in all patients and particularly in the MLD children group. All patients reached the minimum target dose for infusion: median dose of CD34+ cells/kg infused was 10.3 × 10 6 /kg (3.7-25.9), with no difference among the three groups. Bone marrow harvest of volumes > 30 ml/kg in infants and children with ADA-SCID, WAS and MLD is well tolerated and allows obtaining an adequate dose of a medicinal product for HSPC-GT.

Background: Wiskott-Aldrich syndrome is a rare, life-threatening, X-linked primary immunodeficiency characterised by microthrombocytopenia, infections, eczema, autoimmunity, and malignant disease. Lentiviral vector-mediated haemopoietic stem/progenitor cell (HSPC) gene therapy is a potentially curative treatment that represents an alternative to allogeneic HSPC transplantation. Here, we report safety and efficacy data from an interim analysis of patients with severe Wiskott-Aldrich syndrome who received lentiviral vector-derived gene therapy., Methods: We did a non-randomised, open-label, phase 1/2 clinical study in paediatric patients with severe Wiskott-Aldrich syndrome, defined by either WAS gene mutation or absent Wiskott-Aldrich syndrome protein (WASP) expression or a Zhu clinical score of 3 or higher. We included patients who had no HLA-identical sibling donor available or, for children younger than 5 years of age, no suitable 10/10 matched unrelated donor or 6/6 unrelated cord blood donor. After treatment with rituximab and a reduced-intensity conditioning regimen of busulfan and fludarabine, patients received one intravenous infusion of autologous CD34+ cells genetically modified with a lentiviral vector encoding for human WAS cDNA. The primary safety endpoints were safety of the conditioning regimen and safety of lentiviral gene transfer into HSPCs. The primary efficacy endpoints were overall survival, sustained engraftment of genetically corrected HSPCs, expression of vector-derived WASP, improved T-cell function, antigen-specific responses to vaccinations, and improved platelet count and mean platelet volume normalisation. This interim analysis was done when the first six patients treated had completed at least 3 years of follow-up. The planned analyses are presented for the intention-to-treat population. This trial is registered with ClinicalTrials.gov (number NCT01515462) and EudraCT (number 2009-017346-32)., Findings: Between April 20, 2010, and Feb 26, 2015, nine patients (all male) were enrolled of whom one was excluded after screening; the age range of the eight treated children was 1·1-12·4 years. At the time of the interim analysis (data cutoff April 29, 2016), median follow-up was 3·6 years (range 0·5-5·6). Overall survival was 100%. Engraftment of genetically corrected HSPCs was successful and sustained in all patients. The fraction of WASP-positive lymphocytes increased from a median of 3·9% (range 1·8-35·6) before gene therapy to 66·7% (55·7-98·6) at 12 months after gene therapy, whereas WASP-positive platelets increased from 19·1% (range 4·1-31·0) to 76·6% (53·1-98·4). Improvement of immune function was shown by normalisation of in-vitro T-cell function and successful discontinuation of immunoglobulin supplementation in seven patients with follow-up longer than 1 year, followed by positive antigen-specific response to vaccination. Severe infections fell from 2·38 (95% CI 1·44-3·72) per patient-year of observation (PYO) in the year before gene therapy to 0·31 (0·04-1·11) per PYO in the second year after gene therapy and 0·17 (0·00-0·93) per PYO in the third year after gene therapy. Before gene therapy, platelet counts were lower than 20 × 10 9 per L in seven of eight patients. At the last follow-up visit, the platelet count had increased to 20-50 × 10 9 per L in one patient, 50-100 × 10 9 per L in five patients, and more than 100 × 10 9 per L in two patients, which resulted in independence from platelet transfusions and absence of severe bleeding events. 27 serious adverse events in six patients occurred after gene therapy, 23 (85%) of which were infectious (pyrexia [five events in three patients], device-related infections, including one case of sepsis [four events in three patients], and gastroenteritis, including one case due to rotavirus [three events in two patients]); these occurred mainly in the first 6 months of follow-up. No adverse reactions to the investigational drug product and no abnormal clonal proliferation or leukaemia were reported after gene therapy., Interpretation: Data from this study show that gene therapy provides a valuable treatment option for patients with severe Wiskott-Aldrich syndrome, particularly for those who do not have a suitable HSPC donor available., Funding: Italian Telethon Foundation, GlaxoSmithKline, and Orchard Therapeutics., (Copyright © 2019 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd.. All rights reserved.)

Background: To report early and long-term outcomes of patients undergoing minimally invasive mitral valve surgery (MIMVS) through right mini-thoracotomy (RT) over a 10-year period., Methods: From September 2003 to December 2013, a total of 1604 consecutive patients underwent MIMVS through RT., Results: The mean age was 63 ± 13 years, 770 (48 %) patients were female and 218 (13.6 %) had previous cardiac operations. The most predominant pathology was degenerative disease (70 %), followed by functional mitral valve regurgitation (12 %), rheumatic disease (9.4 %), endocarditis (5 %) and prosthetic dysfunction (3.2 %). Mitral valve repair was performed in 1137 (71 %) patients and 476 (29 %) had mitral valve replacement. Direct aortic cannulation was achieved in 1325 (83 %) patients. Among patients with degenerative disease candidate for repair (n = 958), rate of mitral valve repair was 95 %. Repair techniques included annuloplasty (95 %), leafleat resection (63 %), neochordae implantation (16 %) and sliding plasty (11 %). Concomitant procedures included tricuspid valve repair (14.6 %), atrial fibrillation ablation (9.5 %) and atrial septal defect closure (3.2 %). Overall in-hospital mortality was 1.1 %. Thirty-four patients (2.1 %) had conversion to sternotomy. Incidence of stroke was 2 %. Overall survival at 10 years was 88 ± 2 %. Freedom from reoperation at 10 years was 94 ± 2 % for repair and 80 ± 6 % for replacement. Freedom from recurrent mitral regurgitation >3+ at 10 years was 90 ± 3 %., Conclusions: Minimally invasive mitral valve surgery is a safe and reproducible approach associated with low mortality and morbidity, high rate of mitral valve repair and excellent late results.

Background: Mitral valve (MV) repair is the gold standard for the treatment of degenerative MV regurgitation. Recently, minimally invasive mitral valve surgery (MIMVS) has shown excellent postoperative outcomes compared with conventional surgery. The aim of our study is to report early and long-term outcomes of patients undergoing MIMVS through right mini-thoracotomy (RT) over an eight year period., Methods: From September 2003 to December 2011, a total of 1,604 consecutive patients underwent MIMVS through RT., Results: The mean age was 62±13 years, 295 (42%) patients were female and 16 (2.3%) had previous cardiac operations. MV repair was successfully performed in 670 patients, with a rate of success of 95.3%. Repair techniques included annuloplasty (89%), leaflet resection (n=54.2%), neochordae implantation (12.1%), and sliding plasty (10.5%). Overall in-hospital mortality was 0.1%. Incidence of stroke was 1.3%. At eight-year follow-up, overall survival was 90.1%, freedom from reoperation 93%, and freedom from recurrent mitral regurgitation was 90%., Conclusions: MIMV repair through right minithoracotomy is a safe and reproducible procedure associated with high rate of MV repair, and excellent early postoperative and long-term results.

Objectives: Mitral valve (MV) surgery for ischaemic mitral regurgitation (IMR) in patients with depressed left ventricular ejection fraction (LVEF) is associated with poor outcomes. The optimal surgical strategy for IMR in these patients remains controversial. The objective of this study was to compare the early mortality and mid-term survival of MV repair versus MV replacement in patients with IMR and depressed LVEF undergoing coronary artery bypass grafting (CABG)., Methods: A retrospective, observational, cohort study was undertaken of prospectively collected data on 126 consecutive CABG patients with IMR and LVEF <40% undergoing either MV repair (n = 98, 78%) or MV replacement (n = 28, 22%) between July 2002 and February 2011., Results: The overall mortality rate was 7.9% (n = 10). MV replacement was associated with a 4-fold increase in the risk of death compared with MV repair [17.9%, n = 5 vs 5.1%, n = 5; odds ratio (OR) 4.04, 95% confidence interval (CI) 1.08-15.1, P = 0.04]. However, after adjusting for preoperative risk factors, the type of surgical procedure was not an independent risk factor for early mortality (OR 0.1, 95% CI 0.01-31, P = 0.7). Multivariable analysis showed that preoperative LVEF (OR 0.8, 95% CI 0.6-0.9, P = 0.018), preoperative B-type natriuretic peptide (BNP) levels (OR 1.01, 95% CI 1-1.02, P = 0.025), preoperative left ventricle end-systolic diameter (OR 0.8, 95% CI 0.7-1.0, P = 0.05) and preoperative left atrial diameter (OR 1.3, 95% CI 1.0-1.6, P = 0.015) were independent risk factors of early mortality. At the median follow-up of 45 months (interquartile range 20-68 months), the mid-term survival rate was 74% in the MV repair group and 70% in the MV replacement group (P = 0.08). At follow-up, predictors of worse survival were BNP levels [hazard ratio (HR) 1.0, 95% CI 1.0-1.01, P = 0.047], preoperative renal failure (HR 4.6, 95% CI 1.1-20.3, P = 0.039) and preoperative atrial fibrillation (HR 3.3, 95% CI 1.1-10, P = 0.032)., Conclusions: MV repair in CABG patients with IMR and depressed LVEF is not superior to MV replacement with regard to operative early mortality and mid-term survival., (© The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)