Biology subjects

Huggler, K. S.

Publications and source records attributed to Huggler, K. S..

4 recordsLinked to original sources

bioRxiv2025

Human Plasma-Like Medium Promotes Maturation of Human Pluripotent Stem Cell-Derived Cardiomyocytes

Maturing human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) in vitro is critical for advancing drug discovery and cardiotoxicity screening applications of these cells. However, the metabolic compositions of basal media used for hPSC-CM culture typically offer limited relevance to human cardiac physiology. Here, we examined how culture in Human Plasma-Like Medium (HPLM) versus conventional basal media affects the behavior of hPSC-CMs. Starting with Day 16 hPSC-CMs, we cultured cells for two weeks in either HPLM or RPMI-based media and then assessed maturation outcomes at Day 30. Compared to RPMI/B27 media containing either RPMI-defined (11.1 mM) or physiologic glucose levels (5 mM), HPLM/B27 markedly enhanced hPSC-CM maturity as evinced by concerted transcriptomic, structural, functional, and metabolic phenotypes. These effects included a higher extent of myosin heavy chain isoform switching (-MHC to {beta}-MHC), accelerated ventricular-specific myosin light chain isoform switching (MLC2a to MLC2v), elongated sarcomeres, increased multinucleation, enhanced calcium transient kinetics, and coordinated activation of oxidative and glycolytic metabolism. Collectively, these findings demonstrate that medium composition has substantial effects on hPSC-CM biology and also establish HPLM as a tool for driving hPSC-CM maturation in vitro. Translational Impact StatementHPLM was designed to more closely recapitulate the metabolic composition of human plasma and thus provides a physiological platform to promote hPSC-CM maturation. By enhancing structural, functional, and metabolic maturity, HPLM-cultured hPSC-CMs better approximate cardiac physiology, positioning them as improved models for cardiovascular disease research, drug-induced cardiotoxicity screening, and personalized therapeutic testing. This medium can integrate with existing maturation strategies, accelerating the translation of basic cardiac research into clinically predictive tools for the drug development pipeline. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=189 SRC="FIGDIR/small/650456v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@a169eforg.highwire.dtl.DTLVardef@131e6f4org.highwire.dtl.DTLVardef@131d52dorg.highwire.dtl.DTLVardef@a2b248_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2025

Hexokinase detachment from mitochondria drives the Warburg effect to support compartmentalized ATP production

Hexokinase (HK) catalyzes the synthesis of glucose-6-phosphate, marking the first committed step of glucose metabolism. Most cancer cells express two homologous isoforms (HK1 and HK2) that can each bind to the outer mitochondrial membrane (OMM). CRISPR screens across hundreds of cancer cell lines indicate that both are dispensable for cell growth in traditional culture media. By contrast, HK2 deletion impairs cell growth in Human Plasma-Like Medium (HPLM). Here, we find that HK2 is required to maintain sufficient cytosolic (OMM-detached) HK activity under conditions that enhance HK1 binding to the OMM. Notably, OMM-detached rather than OMM-docked HK promotes "aerobic glycolysis" (Warburg effect), an enigmatic phenotype displayed by most proliferating cells. We show that several proposed theories for this phenotype cannot explain the HK2 dependence and instead find that HK2 deletion severely impairs glycolytic ATP production with little impact on total ATP yield for cells in HPLM. Our results reveal a basis for conditional HK2 essentiality and suggest that demand for compartmentalized ATP synthesis underlies the Warburg effect.

cancer biology↗

bioRxiv2021

Clinically-relevant T cell expansion protocols activate distinct cellular metabolic programs and phenotypes

Ex vivo expansion conditions used to generate T cells for immunotherapy are thought to adopt metabolic phenotypes that impede therapeutic efficacy in vivo. The comparison of five different culture media used for clinical T cell expansion revealed unique optima based on different output variables including proliferation, differentiation, function, activation and mitochondrial phenotypes. T cells adapted their metabolism to match their media expansion condition as shown by glucose and glutamine uptake, and patterns of glucose isotope labeling. However, adoption of these metabolic phenotypes was uncoupled to T cell function. Furthermore, T cell products cultured in ascites from ovarian cancer patients displayed suppressed mitochondrial activity and function irrespective of the ex vivo expansion media. In one case, culturing in ascites resulted in increased glucose uptake which was insufficient to rescue T cell function. Thus, ex vivo T cell expansion conditions have profound impacts on metabolism and function.

immunology↗

bioRxiv2020

CRISPR screens in physiologic medium reveal conditionally essential genes in human cells

Forward genetic screens across hundreds of diverse cancer cell lines have started to define the genetic dependencies of proliferating human cells and how these vary by genotype and lineage. Most screens, however, have been carried out in culture media that poorly resemble metabolite availability in human blood. To explore how medium composition influences gene essentiality, we performed CRISPR-based screens of human cancer cell lines cultured in traditional versus human plasma-like medium (HPLM). Sets of medium-dependent fitness genes span several cellular processes and can vary with both natural cell-intrinsic diversity and the specific combination of basal and serum components that comprise typical culture media. Notably, we traced the causes for each of three conditional growth phenotypes to the availability of metabolites uniquely defined in HPLM versus traditional media. Our findings reveal the profound impact of medium composition on gene essentiality in human cells, and also suggest general strategies for using genetic screens in HPLM to uncover new cancer vulnerabilities and gene-nutrient interactions.

cancer biology↗