Partition coefficient screening - An effective approach for finding the best conditions for byproduct removal as demonstrated by a bispecific antibody purification case.

In recombinant protein purification, differences in isoelectric point (pI)/surface charge and hydrophobicity between the product and byproducts generally form the basis for separation. For bispecific antibodies (bsAbs), in many cases the physicochemical difference between product and byproducts is subtle, making byproduct removal considerably challenging. In a previous report, with a bsAb case study, we showed that partition coefficient (Kp) screening for the product and byproducts under various conditions facilitated finding conditions under which effective separation of two difficult-to-remove byproducts was achieved by anion exchange (AEX) chromatography. In the current work, as a follow-up study, we demonstrated that the same approach enabled identification of conditions allowing equally good byproduct removal by mixed-mode chromatography with remarkably improved yield. Results from the current and previous studies proved that separation factor determination based on Kp screening for product and byproduct is an effective approach for finding conditions enabling efficient and maximum byproduct removal, especially in challenging cases.

Ciliary localization of GPR75 promotes fat accumulation in mice.

Obesity is a growing public health concern that affects the longevity and lifestyle of all human populations including children and older individuals. Diverse factors drive obesity, making it challenging to understand and treat. While recent studies highlight the importance of GPCR signaling for metabolism and fat accumulation, we lack a molecular description of how obesogenic signals accumulate and propagate in cells, tissues, and organs. In this issue of the JCI, Jiang et al. utilized germline mutagenesis to generate a missense variant of GRP75, encoded by the Thinner allele, which resulted in mice with a lean phenotype. GPR75 accumulated in the cilia of hypothalamic neurons. However, mice with the Thinner allele showed defective ciliary localization with resistance to fat accumulation. Additionally, GPR75 regulation of fat accumulation appeared independent of leptin and ADCY3 signaling. These findings shed light on the role of GPR75 in fat accumulation and highlight the need to identify relevant ligands.

Characterization and Potential Relevance of Randomized Controlled Trial Patient Populations in Revision Total Joint Arthroplasty: A Systematic Review.

INTRODUCTION: Randomized controlled trial (RCT) studies in revision total joint arthroplasty (rTJA) are essential to investigate the effectiveness of interventions. However, there has been limited research investigating how patient cohorts comprising rTJA RCT samples resemble the US patient population undergoing rTJA in terms of demographic and clinical characteristics. Thus, the purpose of this systematic review was to compare the patient characteristics of rTJA RCT cohorts with the characteristics of national patient database cohorts. METHODS: RCT studies for rTJA were aggregated. Patient demographics in this group were compared against HCUP NIS and ACS-NSQIP patient cohorts. RESULTS: Forty-six RCTs met inclusion criteria. There were 3,780 total patients across 46 RCTs. The average age of patients in the rTJA RCT cohort was 66.4 9.4 while the NIS cohort was 67.3 11.1 (d=0.08, effect size=small). The average BMI of the rTJA RCT cohort was 31.1 5.7 while the NSQIP cohort was 31.7 8.3 (d=0.08, effect size=small). For rTJA, effect sizes for age, BMI, sex, ethnicity, smoking, and diabetes were all small or very small. CONCLUSIONS: Overall, the rTJA RCT patient cohort does not differ significantly compared to the general patient population undergoing rTJA. Differences in demographic and clinical characteristics between the rTJA RCT cohort and database cohorts were minimal to small, indicating that these differences are unlikely to impact clinical outcomes.

Molecular and functional landscape of malignant serous effusions for precision oncology.

Personalized treatment for patients with advanced solid tumors critically depends on the deep characterization of tumor cells from patient biopsies. Here, we comprehensively characterize a pan-cancer cohort of 150 malignant serous effusion (MSE) samples at the cellular, molecular, and functional level. We find that MSE-derived cancer cells retain the genomic and transcriptomic profiles of their corresponding primary tumors, validating their use as a patient-relevant model system for solid tumor biology. Integrative analyses reveal that baseline gene expression patterns relate to global ex vivo drug sensitivity, while high-throughput drug-induced transcriptional changes in MSE samples are indicative of drug mode of action and acquired treatment resistance. A case study exemplifies the added value of multi-modal MSE profiling for patients who lack genetically stratified treatment options. In summary, our study provides a functional multi-omics view on a pan-cancer solid tumor cohort and underlines the feasibility and utility of MSE-based precision oncology.

Very High Early Failure Rate Following Primary Repair of Acute Extensor Mechanism Disruption After Total Knee Arthroplasty.

INTRODUCTION: Extensor mechanism disruption is a devastating complication following total knee arthroplasty (TKA). Despite its morbidity, there is no consensus regarding the optimal treatment strategy. We aimed to determine the survivorship, clinical outcomes, and improvement in patient-reported outcome measures (PROMs) after primary repair of acute extensor mechanism disruptions following primary or revision TKA. METHODS: A retrospective review identified 41 acute extensor mechanism disruptions (33 primary TKAs and eight revision TKAs) from 2015 to 2021. The study group was 56% women, the mean BMI was 33, the mean age was 66 years, and the mean follow-up was three years. Extensor mechanism disruption occurred at the patellar tendon (n = 17), quadriceps tendon (n = 15), and patella (n = 9) at a mean of 10 months following TKA. Surgical management was primary repair (n = 30) or primary repair with augmentation (allograft or autograft) (n = 11). Kaplan-Meier analysis estimated survivorship. RESULTS: The two-year survivorship free from all-cause reoperation was 72 and 23% following primary and revision TKA, respectively (P = 0.013). The two-year survivorship free from all-cause reoperation was 66% for primary repair versus 61% for primary repair with augmentation (P = 0.95). There were 17 (41%) patients who underwent reoperation, most commonly for re-rupture (n = 4) in two primary repairs and two primary repairs with augmentation (P = 0.288). Revision TKA (P = 0.049) and increased time from disruption to repair (P = 0.039) were risk factors for reoperation. The mean extensor lag did not significantly improve, nor did patients see improvement in their PROMs. CONCLUSION: After primary and revision TKA, acute extensor mechanism disruption treated with primary repair with or without augmentation had very poor early survivorship free from all-cause reoperation. Patients should be counseled appropriately, and alternative surgical techniques should be considered.

AKT and EZH2 inhibitors kill TNBCs by hijacking mechanisms of involution.

Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype and has the highest rate of recurrence1. The predominant standard of care for advanced TNBC is systemic chemotherapy with or without immunotherapy; however, responses are typically short lived1,2. Thus, there is an urgent need to develop more effective treatments. Components of the PI3K pathway represent plausible therapeutic targets; more than 70% of TNBCs have alterations in PIK3CA, AKT1 or PTEN3-6. However, in contrast to hormone-receptor-positive tumours, it is still unclear whether or how triple-negative disease will respond to PI3K pathway inhibitors7. Here we describe a promising AKT-inhibitor-based therapeutic combination for TNBC. Specifically, we show that AKT inhibitors synergize with agents that suppress the histone methyltransferase EZH2 and promote robust tumour regression in multiple TNBC models in vivo. AKT and EZH2 inhibitors exert these effects by first cooperatively driving basal-like TNBC cells into a more differentiated, luminal-like state, which cannot be effectively induced by either agent alone. Once TNBCs are differentiated, these agents kill them by hijacking signals that normally drive mammary gland involution. Using a machine learning approach, we developed a classifier that can be used to predict sensitivity. Together, these findings identify a promising therapeutic strategy for this highly aggressive tumour type and illustrate how deregulated epigenetic enzymes can insulate tumours from oncogenic vulnerabilities. These studies also reveal how developmental tissue-specific cell death pathways may be co-opted for therapeutic benefit.

Integrating spatial profiles and cancer genomics to identify immune-infiltrated mismatch repair proficient colorectal cancers.

Predicting the progression of solid cancers based solely on genetics is challenging due to the influence of the tumor microenvironment (TME). For colorectal cancer (CRC), tumors deficient in mismatch repair (dMMR) are more immune infiltrated than mismatch repair proficient (pMMR) tumors and have better prognosis following resection. Here we quantify features of the CRC TME by combining spatial profiling with genetic analysis and release our findings via a spatially enhanced version of cBioPortal that facilitates multi-modal data exploration and analysis. We find that ∼20% of pMMR tumors exhibit similar levels of T cell infiltration as dMMR tumors and that this is associated with better survival but not any specific somatic mutation. These T cell-infiltrated pMMR (tipMMR) tumors contain abundant cells expressing PD1 and PDL1 as well as T regulatory cells, consistent with a suppressed immune response. Thus, like dMMR CRC, tipMMR CRC may benefit from immune checkpoint inhibitor therapy. SIGNIFICANCE: pMMR tumors with high T cell infiltration and active immunosuppression are identifiable with a mid-plex imaging assay whose clinical deployment might double the number of treatment-naïve CRCs eligible for ICIs. Moreover, the low tumor mutational burden in tipMMR CRC shows that MMR status is not the only factor promoting immune infiltration.

The human ciliopathy protein RSG1 links the CPLANE complex to transition zone architecture.

Cilia are essential organelles and variants in genes governing ciliary function result in ciliopathic diseases. The Ciliogenesis and PLANar polarity Effectors (CPLANE) protein complex is essential for ciliogenesis in animals models but remains poorly defined. Notably, all but one subunit of the CPLANE complex have been implicated in human ciliopathy. Here, we identify three families in which variants in the remaining CPLANE subunit CPLANE2/RSG1 also cause ciliopathy. These patients display cleft palate, tongue lobulations and polydactyly, phenotypes characteristic of Oral-Facial-Digital Syndrome. We further show that these alleles disrupt two vital steps of ciliogenesis, basal body docking and recruitment of intraflagellar transport proteins. Moreover, APMS reveals that Rsg1 binds the CPLANE and also the transition zone protein Fam92 in a GTP-dependent manner. Finally, we show that CPLANE is generally required for normal transition zone architecture. Our work demonstrates that CPLANE2/RSG1 is a causative gene for human ciliopathy and also sheds new light on the mechanisms of ciliary transition zone assembly.

Multimodal Spatial Profiling Reveals Immune Suppression and Microenvironment Remodeling in Fallopian Tube Precursors to High-Grade Serous Ovarian Carcinoma.

High-Grade Serous Ovarian Cancer (HGSOC) originates from fallopian tube (FT) precursors. However, the molecular changes that occur as precancerous lesions progress to HGSOC are not well understood. To address this, we integrated high-plex imaging and spatial transcriptomics to analyze human tissue samples at different stages of HGSOC development, including p53 signatures, serous tubal intraepithelial carcinomas (STIC), and invasive HGSOC. Our findings reveal immune modulating mechanisms within precursor epithelium, characterized by chromosomal instability, persistent interferon (IFN) signaling, and dysregulated innate and adaptive immunity. FT precursors display elevated expression of MHC-class I, including HLA-E, and IFN-stimulated genes, typically linked to later-stage tumorigenesis. These molecular alterations coincide with progressive shifts in the tumor microenvironment, transitioning from immune surveillance in early STICs to immune suppression in advanced STICs and cancer. These insights identify potential biomarkers and therapeutic targets for HGSOC interception and clarify the molecular transitions from precancer to cancer. STATEMENT OF SIGNIFICANCE: This study maps the immune response in fallopian tube precursors of high-grade serous ovarian cancer, highlighting localized interferon signaling, CIN, and competing immune surveillance and suppression along the progression axis. It provides an explorable public spatial profiling atlas for investigating precancer mechanisms, biomarkers, and early detection and interception strategies.

The Bronchoalveolar Lavage Dilution Conundrum: An Updated View on a Long-Standing Problem.

Bronchoalveolar lavage (BAL) is used by researchers to study molecular interactions within healthy and diseased human lungs. However, the utility of BAL fluid measurements may be limited by difficulties accounting for dilution of the epithelial lining fluid (ELF) sampled and inconsistent collection techniques. The use of endogenous markers to estimate ELF dilution has been proposed as a potential method to normalize acellular molecule measurements in BAL fluid, but these markers are also imperfect and prone to inaccuracy. The focus of this report is to review factors that affect the interpretation of acellular molecule measurements in lung ELF and present original data comparing the performance of several BAL dilution markers during health and in a human endobronchial endotoxin challenge model of acute inflammation. Our findings suggest that incomplete ELF and lavage fluid mixing, flux of markers across the alveolar barrier, and lung inflammation are all possible factors that can affect marker performance. Accounting for these factors, we show that commonly used markers including urea, total protein, albumin, and immunoglobulin M are likely unreliable BAL dilution markers. In contrast, surfactant protein D, appears to be less affected by these factors and may be a more accurate and biologically plausible marker to improve the reproducibility of acellular BAL component measurements across individuals, during health and inflammatory states.

Vaccine hesitancy among parents of children in their first two years of life.

Background: Vaccine hesitancy is considered a primary cause of outbreaks of vaccine-preventable infectious diseases. The Austrian vaccination plan includes 24 vaccinations in the first 2 years of life, 12 for free and 12 subject to a fee. Since preterm babies are more susceptible to severe infections, immunization is a vital protection strategy. This study examines the routine immunization schedule recommended for children in Austria, the number of timely vaccinations, and the number of delayed and rejected vaccinations. Possible reasons for vaccination delays and rejection and potential influencing factors (preterm birth, COVID-19 pandemic, information sources) are also analyzed. Methods: We included children aged 2 to 5 years who presented to Vienna's largest pediatric center with an Austrian mother-child pass and spent the first 2 years of their lives in Austria. Data was collected using questionnaires about the vaccination status, parents' reasons for any rejections or delays in the recommended vaccination regimen, the impact of the COVID-19 pandemic on individuals' vaccination behavior, and child-specific influencing factors such as preterm birth and socioeconomic factors. Results: 90% of the 150 study subjects follow the recommendations on routine vaccinations, while 40-62% accept vaccinations subject to a fee. Preterm infants received less fee-based (53%) as well as gratuitous (88%) vaccinations. While free vaccinations tend to be delayed, more fee based vaccinations are rejected. With free vaccinations, delays and refusals occur due to illness or missed appointments. In the case of fee- required vaccinations, however, fears of side effects are also one of the main reasons. Due to the COVID-19 pandemic, about a quarter of parents have become more skeptical about vaccines. However, the vaccination rate of premature babies is usually just below that of full-term babies. Physicians remain the most trustworthy source of information about vaccinations. Conclusion: Free vaccinations are more accepted by parents than fee based vaccinations. Preterm babies, which are a high risk group for vaccination preventable diseases, show a lower or delayed vaccination rate, which must be prevented through intensive doctor education. In addition, vaccination hesitancy changed during the COVID-19 pandemic, which needs to be addressed during the medical consultation.

Carcinoplaxmistio Ng & Mitra, 2019 (Crustacea, Decapoda, Goneplacidae): additional records and genetic differentiation of allied taxa.

The goneplacid crab, Carcinoplaxmistio Ng & Mitra, 2019, was originally described from West Bengal, India, in the northern Indian Ocean. Additional material of C.mistio from off Tamil Nadu in the southeast of India revealed a high degree of size-associated variation in the structures of the anterolateral tooth of the carapace, chelipeds, and male and female pleons. In addition to an in-depth morphological examination of C.mistio, this study also records the natural coloration of the species and conducts a genetic comparison (with mitochondrial COI and 16S rRNA genes) with its close relatives, C.haswelli (Miers, 1884) and C.purpurea Rathbun, 1914. Molecular comparison of C.mistio with its morphologically closest congener, C.haswelli from northern Australia and the western Pacific, corroborates their status as separate species. The genetic sequence of C.mistio, however, is similar to that of C.purpurea from the West Pacific, although these two species can easily be distinguished by distinct carapace and ambulatory leg characters. The present study provides some possible explanations for the genetic and morphological incongruence observed between C.mistio and C.purpurea and highlights the need for a detailed molecular study for Carcinoplax H. Milne Edwards, 1852, to appreciate the evolution of various morphological characters in the genus.

Cross-Cultural Differences in the Pathways to Internet Gaming Disorder.

BACKGROUND: No research to date has examined cross-cultural differences in the pathways to internet gaming disorder (IGD). The current study aimed to address this limitation by examining the relationships between nationality (Singaporeans vs. Australians), culture orientation, gaming motivations, and IGD. METHODS: Participants were 101 Singaporeans (55.4% males) and 98 Australians (52.0% males). They completed the Culture Orientation Scale, the Motives for Online Gaming Questionnaire, and the Internet Gaming Disorder Scale-Short-Form. RESULTS: A series of mediational analyses showed that Singaporeans tend to be more collectivistic (both horizontally and vertically). In turn, this culture orientation motivates them to play games for social reasons, increasing the risk for IGD. In contrast, Australians tend to be more individualistic (vertically only). In turn, this culture orientation motivates them to play games for competitive reasons, increasing the risk for IGD. CONCLUSION: Limitations include the use of samples from two countries only, precluding a generalization of the results. Future research directions include examining the role of game genres as a mediator in the nationality-IGD relationship.

Medicaid Accountable Care Organizations and Disparities in Pediatric Asthma Care.

Importance: Nearly 6 million children in the US have asthma, and over one-third of US children are insured by Medicaid. Although 23 state Medicaid programs have experimented with accountable care organizations (ACOs), little is known about ACOs' effects on longstanding insurance-based disparities in pediatric asthma care and outcomes. Objective: To determine associations between Massachusetts Medicaid ACO implementation in March 2018 and changes in care quality and use for children with asthma. Design, Setting, and Participants: Using data from the Massachusetts All Payer Claims Database from January 1, 2014, to December 31, 2020, we determined child-years with asthma and used difference-in-differences (DiD) estimates to compare asthma quality of care and emergency department (ED) or hospital use for child-years with Medicaid vs private insurance for 3 year periods before and after ACO implementation for children aged 2 to 17 years. Regression models accounted for demographic and community characteristics and health status. Data analysis was conducted between January 2022 and June 2024. Exposure: Massachusetts Medicaid ACO implementation. Main Outcomes and Measures: Primary outcomes were binary measures in a calendar year of (1) any routine outpatient asthma visit, (2) asthma medication ratio (AMR) greater than 0.5, and (3) any ED or hospital use with asthma. To determine the statistical significance of differences in descriptive statistics between groups, χ2 and t tests were used. Results: Among 376 509 child-year observations, 268 338 (71.27%) were insured by Medicaid and 73 633 (19.56%) had persistent asthma. There was no significant change in rates of routine asthma visits for Medicaid-insured child-years vs privately insured child-years post-ACO implementation (DiD, -0.4 percentage points [pp]; 95% CI, -1.4 to 0.6 pp). There was an increase in the proportion with AMR greater than 0.5 for Medicaid-insured child-years vs privately insured in the postimplementation period (DiD, 3.7 pp; 95% CI, 2.0-5.4 pp), with absolute declines in both groups postimplementation. There was an increase in any ED or hospital use for Medicaid-insured child-years vs privately insured postimplementation (DiD, 2.1 pp; 95% CI, 1.2-3.0 pp), an 8% increase from the preperiod Medicaid use rate. Conclusions and Relevance: Introduction of Massachusetts Medicaid ACOs was associated with persistent insurance-based disparities in routine asthma visit rates; a narrowing in disparities in appropriate AMR rates due to reductions in appropriate rates among those with private insurance; and worsening disparities in any ED or hospital use for Medicaid-insured children with asthma compared to children with private insurance. Continued study of changes in pediatric asthma care delivery is warranted in relation to major Medicaid financing and delivery system reforms.

Cyto-architecture of Byblis glands and leaf cells based on freeze-substitution and conventional TEM.

BACKGROUND AND AIMS: Byblis liniflora (Byblidaceae) is a carnivorous plant that has developed sticky fly paper traps with two types of glandular trichomes producing digestive enzymes and sticky mucilage. This study aimed to analyze the ultrastructure of these glandular leaf trichomes based on rapid freeze fixation and conventional chemical fixation in the attempt to understand their functional contribution to the carnivorous performance of the plants. METHODS: The Byblis cells were studied in TEM, SEM and STEM using cryo techniques for fixation and substitution in addition to conventional chemical fixation. KEY RESULTS: We show in detail the architecture of both the digestive glands and the mucilage glands with their relevant sets of organelles. Both mitochondria and plastids have a conspicuous plasticity, with branches and constrictions, and they associate to form clusters. The glandular cells appear to be transfer cells with cell wall ingrowths. Digestive glands occur in different states of development. Their cuticle forms discontinuities which are unique among glands of carnivorous plants. They look like cuticular holes -- the cuticle separates from the cell wall in only one spot and then ruptures. Cuticular discontinuities thus differ from cuticular gaps and cuticular pores so far described in carnivorous plants. We therefore propose for them the term cuticular holes. CONCLUSIONS: Application of cryo-techniques made it possible to show the true structure of the cell wall and the relationship between cell wall ingrowths and organelles, as well as the morphology and structure of organelles and their associations.

Integrative multiomic approaches reveal ZMAT3 and p21 as conserved hubs in the p53 tumor suppression network.

TP53 , the most frequently mutated gene in human cancer, encodes a transcriptional activator that induces myriad downstream target genes. Despite the importance of p53 in tumor suppression, the specific p53 target genes important for tumor suppression remain unclear. Recent studies have identified the p53-inducible gene Zmat3 as a critical effector of tumor suppression, but many questions remain regarding its p53-dependence, activity across contexts, and mechanism of tumor suppression alone and in cooperation with other p53-inducible genes. To address these questions, we used Tuba-seq Ultra somatic genome editing and tumor barcoding in a mouse lung adenocarcinoma model, combinatorial in vivo CRISPR/Cas9 screens, meta-analyses of gene expression and Cancer Dependency Map data, and integrative RNA-sequencing and shotgun proteomic analyses. We established Zmat3 as a core component of p53-mediated tumor suppression and identified Cdkn1a as the most potent cooperating p53-induced gene in tumor suppression. We discovered that ZMAT3/CDKN1A serve as near-universal effectors of p53-mediated tumor suppression that regulate cell division, migration, and extracellular matrix organization. Accordingly, combined Zmat3 - Cdkn1a inactivation dramatically enhanced cell proliferation and migration compared to controls, akin to p53 inactivation. Together, our findings place ZMAT3 and CDKN1A as hubs of a p53-induced gene program that opposes tumorigenesis across various cellular and genetic contexts.

Optical Properties and Growth Characteristics of 8-Quinolinolato Lithium (Liq) Nano-Layers Deposited by Gas Transport Deposition.

Organometallic complexes containing reactive alkali metals, such as lithium (Li), represent a promising material approach for electron injection layers and electron transport layers (EILs and ETLs) to enhance the performance of Organic Light-Emitting Diodes (OLEDs). 8-Quinolinolato Lithium (Liq) has shown remarkable potential as an EIL and ETL when conveyed in very thin films. Nevertheless, the deposition of nano-layers requires precise control over both thickness and morphology. In this work, we investigate the optical properties and morphological characteristics of Liq thin films deposited via Organic Vapor Phase Deposition (OVPD). Specifically, we present our methodology for analyzing the measured pseudodielectric function <ε(ω)> using Spectroscopic Ellipsometry (SE), alongside the nano-topography of evaporated Liq nano-layers using Atomic Force Microscopy (AFM). This information can contribute to the understanding of the functionality of this material, since ultra-thin Liq interlayers can significantly increase the operational stability of OLED architectures.

Hepatic mitochondrial and peroxisomal alterations in acutely ill malnourished Malawian children: A postmortem cohort study.

Objectives: To describe and compare liver mitochondrial and peroxisomal histopathology by nutritional status in children who died following hospitalization for acute illness in Malawi. Methods: Liver tissue was collected using Minimally Invasive Tissue Sampling from eleven children under-five years old who died during hospitalization and were either non-wasted (n = 4), severely wasted (n = 4) or had edematous malnutrition (n = 3). Histology was assessed on hematoxylin and eosin stained slides. Mitochondrial and peroxisomal ultrastructural features were characterized using electron microscopy (EM) and immunofluorescence (IF). Results: Hepatic steatosis was present in 50 % of non-wasted and severely wasted children and all children with edematous malnutrition. Edematous malnutrition was associated with 56 % and 45 % fewer mitochondria than severe wasting (p < 0.001) and no wasting (p = 0.006), respectively, and abnormal mitochondrial morphology compared to severe wasting (p = 0.002) and no wasting (p = 0.035). Peroxisomal abundance was reduced in edematous malnutrition compared to severe wasting (p = 0.005), but did not differ from no-wasting. Conclusion: Edematous malnutrition is associated with reduced abundance and altered morphology of hepatic mitochondria and peroxisomes. Interventions targeting improvements in hepatic metabolic function may be beneficial in improving metabolism and reducing mortality in children with severe malnutrition, particularly in those with nutritional edema.

Organoid culture promotes dedifferentiation of mouse myoblasts into stem cells capable of complete muscle regeneration.

Experimental cell therapies for skeletal muscle conditions have shown little success, primarily because they use committed myogenic progenitors rather than true muscle stem cells, known as satellite cells. Here we present a method to generate in vitro-derived satellite cells (idSCs) from skeletal muscle tissue. When transplanted in small numbers into mouse muscle, mouse idSCs fuse into myofibers, repopulate the satellite cell niche, self-renew, support multiple rounds of muscle regeneration and improve force production on par with freshly isolated satellite cells in damaged skeletal muscle. We compared the epigenomic and transcriptional signatures between idSCs, myoblasts and satellite cells and used these signatures to identify core signaling pathways and genes that confer idSC functionality. Finally, from human muscle biopsies, we successfully generated satellite cell-like cells in vitro. After further development, idSCs may provide a scalable source of cells for the treatment of genetic muscle disorders, trauma-induced muscle damage and age-related muscle weakness.