Influence Cell Fate Research Articles

The mechanical journey of primordial germ cells.

Primordial germ cells (PGCs) are the earliest progenitors of germline cells of the gonads in animals. The tissues that arise from primordial germ cells give rise to the male as well as female gametes and are thus responsible for transmitting genetic information to subsequent generations. Their development from single cells to fully formed tissues has thus been of great importance. In most higher animals, PGCs are initially specified at a site away from the gonads. They then migrate across multiple tissue contexts to reach a mesodermal mass of cells called the genital ridge, where they associate with somatic cells to form the sex-specific reproductive organs. This migratory behavior has been studied extensively to identify the various tissues PGCs interact with and how this might affect their development. A crucial point overlooked by classical studies has been the physical environment experienced by PGCs as they migrate and the mechanical challenges they might encounter. It has long been understood that migrating cells can sense and adapt to physical forces around them via a variety of mechanisms. Studies have also shown that these mechanical signals can guide stem cell fate. In this review, we summarize the mechanical microenvironment of migrating PGCs in different organisms. We describe how cells can adapt to this environment and how this adaptation can influence cell fate. We propose that mechanical signals play a crucial role in normal development of the germline and shed light on this unexplored area of developmental biology.

Inertial effect of cell state velocity on the quiescence-proliferation fate decision

Energy landscapes can provide intuitive depictions of population heterogeneity and dynamics. However, it is unclear whether individual cell behavior, hypothesized to be determined by initial position and noise, is faithfully recapitulated. Using the p21-/Cdk2-dependent quiescence-proliferation decision in breast cancer dormancy as a testbed, we examined single-cell dynamics on the landscape when perturbed by hypoxia, a dormancy-inducing stress. Combining trajectory-based energy landscape generation with single-cell time-lapse microscopy, we found that a combination of initial position and velocity on a p21/Cdk2 landscape, but not position alone, was required to explain the observed cell fate heterogeneity under hypoxia. This is likely due to additional cell state information such as epigenetic features and/or other species encoded in velocity but missing in instantaneous position determined by p21 and Cdk2 levels alone. Here, velocity dependence manifested as inertia: cells with higher cell cycle velocities prior to hypoxia continued progressing along the cell cycle under hypoxia, resisting the change in landscape towards cell cycle exit. Such inertial effects may markedly influence cell fate trajectories in tumors and other dynamically changing microenvironments where cell state transitions are governed by coordination across several biochemical species.

Metabolic Stress Levels Influence the Ability of Myelin Transcription Factors to Regulate β-Cell Identity and Survival.

A hallmark of type 2 diabetes (T2D) is endocrine islet β-cell failure, which can occur via cell dysfunction, loss-of-identity, and/or death. How each is induced remains largely unknown. Here, we use mouse β-cells that are deficient for Myelin transcription factors (Myt TFs, including Myt1, 2, and 3) to address this question. We have reported that inactivating all three Myt genes in pancreatic progenitor cells (MytPancΔ) causes β-cell failure and late onset diabetes in mice. Their lower expression in human β-cells is correlated with β-cell dysfunction and SNPs in MYT2 and MYT3 are associated in higher risk of T2D. We now show that these Myt TF-deficient postnatal β-cells also de-differentiate by reactivating several progenitor markers. Intriguingly, mosaic Myt TF inactivation in only a portion of islet β-cells does not results in overt diabetes, but this creates a condition where Myt TF-deficient β-cells stay alive while activating several markers of Ppy-expressing islet cells. By transplanting MytPancΔ islets into the anterior eye chambers of immune-compromised mice, we directly show that glycemic and obesity-related conditions influence cell fate, with euglycemia inducing several Ppy+ cell markers while hyperglycemia and insulin resistance inducing additional cell death. These findings suggest that the observed β-cell defects in T2D depend on not only their inherent genetic/epigenetic defects, but also the metabolic load.

Lactylation: A Novel Post-Translational Modification with Clinical Implications in CNS Diseases.

Lactate, an important metabolic product, provides energy to neural cells during energy depletion or high demand and acts as a signaling molecule in the central nervous system. Recent studies revealed that lactate-mediated protein lactylation regulates gene transcription and influences cell fate, metabolic processes, inflammation, and immune responses. This review comprehensively examines the regulatory roles and mechanisms of lactylation in neurodevelopment, neuropsychiatric disorders, brain tumors, and cerebrovascular diseases. This analysis indicates that lactylation has multifaceted effects on central nervous system function and pathology, particularly in hypoxia-induced brain damage. Highlighting its potential as a novel therapeutic target, lactylation may play a significant role in treating neurological diseases. By summarizing current findings, this review aims to provide insights and guide future research and clinical strategies for central nervous system disorders.

Manipulating long-term fates of sonoporated cells by regulating intracellular calcium for improving sonoporation-based delivery

Sonoporation-based delivery has great promise for noninvasive drug and gene therapy. After short-term membrane resealing, the long-term function recovery of sonoporated cells affects the efficiency and biosafety of sonoporation-based delivery. It is necessary to identify the key early biological signals that influence cell fate and to develop strategies for manipulating the long-term fates of sonoporated cells. Here, we used a customized experimental platform with a single cavitating microbubble induced by a single ultrasound pulse (frequency: 1.5 MHz, pulse length:13.33 μs, peak negative pressure: ∼0.40 MPa) to elicit single-site reversible sonoporation on a single HeLa cell model. We used a living-cell microscopic imaging system to trace the long-term fates of sonoporated HeLa cells in real-time for 48 h. Fluorescence from intracellular propidium iodide and Fluo-4 was used to evaluate the degree of sonoporation and intracellular calcium fluctuation (ICF), respectively. Changes in cell morphology were used to assess the long-term cell fates (i.e., proliferation, arrest, or death). We found that heterogeneously sonoporated cells had different long-term fates. With increasing degree of sonoporation, the probability of normal (proliferation) and abnormal fates (arrest and death) in sonoporated cells decreased and increased, respectively. We identified ICF as an important early event for triggering different long-term fates. Reversibly sonoporated cells exhibited stronger proliferation and restoration at lower extents of ICF. We then regulated ICF dynamics in sonoporated cells using 2-APB or BAPTA treatment to reduce calcium release from intracellular organelles and enhance intracellular calcium clearance, respectively. This significantly enhanced the proliferation and restoration of sonoporated cells and reduced the occurrence of cell-cycle arrest and death. Finally, we found that the long-term fates of sonoporated cells at multiple sites and neighboring cells were also dependent on the extent of ICF, and that 2-APB significantly enhanced their viability and reduced death. Thus, using a single HeLa cell model, we demonstrated that regulating intracellular calcium can effectively enhance the proliferation and restoration capabilities of sonoporated cells, therefore rescuing the long-term viability of sonoporated cells. These findings add to our understanding of the biophysical process of sonoporation and help design new strategies for improving the efficiency and biosafety of sonoporation-based delivery.

SYS-1/beta-catenin inheritance and regulation by Wnt-signaling during asymmetric cell division.

Asymmetric cell division (ACD) allows daughter cells of a polarized mother to acquire different developmental fates. In C. elegans , the Wnt/β-catenin Asymmetry (WβA) pathway oversees many embryonic and larval ACDs; here, a Wnt gradient induces an asymmetric distribution of Wnt signaling components within the dividing mother cell. One terminal nuclear effector of the WβA pathway is the transcriptional activator SYS-1/β-catenin. SYS-1 is sequentially negatively regulated during ACD; first by centrosomal regulation and subsequent proteasomal degradation and second by asymmetric activity of the β-catenin "destruction complex" in one of the two daughter cells, which decreases SYS-1 levels in the absence of WβA signaling. However, the extent to which mother cell SYS-1 influences cell fate decisions of the daughters is unknown. Here, we quantify inherited SYS-1 in the differentiating daughter cells and the role of SYS-1 inheritance in Wnt-directed ACD. Photobleaching experiments demonstrate the GFP::SYS-1 present in daughter cell nuclei is comprised of inherited and de novo translated SYS-1 pools. We used a photoconvertible DENDRA2::SYS-1, to directly observe the dynamics of inherited SYS-1. Photoconversion during mitosis reveals that SYS-1 clearance at the centrosome preferentially degrades older SYS-1, and this accumulation is regulated via dynein trafficking. Photoconversion of the EMS cell during Wnt-driven ACD shows daughter cell inheritance of mother cell SYS-1. Additionally, loss of centrosomal SYS-1 increased inherited SYS-1 and, surprisingly, loss of centrosomal SYS-1 also resulted in increased levels of de novo SYS-1 in both EMS daughter cells. Lastly, we show that daughter cell negative regulation of SYS-1 via the destruction complex member APR-1/APC is key to limit both the de novo and the inherited SYS-1 pools in both the E and the MS cells. We conclude that regulation of both inherited and newly translated SYS-1 via centrosomal processing in the mother cell and daughter cell regulation via Wnt signaling are critical to maintain sister SYS-1 asymmetry during ACD.

PRMT6 Epigenetically Drives Metabolic Switch from Fatty Acid Oxidation toward Glycolysis and Promotes Osteoclast Differentiation During Osteoporosis.

Epigenetic regulation of metabolism profoundly influences cell fate commitment. During osteoclast differentiation, the activation of RANK signaling is accompanied by metabolic reprogramming, but the epigenetic mechanisms by which RANK signaling induces this reprogramming remain elusive. By transcriptional sequence and ATAC analysis, this study identifies that activation of RANK signaling upregulates PRMT6 by epigenetic modification, triggering a metabolic switching from fatty acids oxidation toward glycolysis. Conversely, Prmt6 deficiency reverses this shift, markedly reducing HIF-1α-mediated glycolysis and enhancing fatty acid oxidation. Consequently, PRMT6 deficiency or inhibitor impedes osteoclast differentiation and alleviates bone loss in ovariectomized (OVX) mice. At the molecular level, Prmt6 deficiency reduces asymmetric dimethylation of H3R2 at the promoters of genes including Ppard, Acox3, and Cpt1a, enhancing genomic accessibility for fatty acid oxidation. PRMT6 thus emerges as a metabolic checkpoint, mediating metabolic switch from fatty acid oxidation to glycolysis, thereby supporting osteoclastogenesis. Unveiling PRMT6's critical role in epigenetically orchestrating metabolic shifts in osteoclastogenesis offers a promising target for anti-resorptive therapy.

A CRISPR/Cas9 screen in embryonic stem cells reveals that Mdm2 regulates totipotency exit

During early embryonic development, the transition from totipotency to pluripotency is a fundamental and critical process for proper development. However, the regulatory mechanisms governing this transition remain elusive. Here, we conducted a comprehensive genome-wide CRISPR/Cas9 screen to investigate the 2-cell-like cells (2CLCs) phenotype in mouse embryonic stem cells (mESCs). This effort led to the identification of ten regulators that play a pivotal role in determining cell fate during this transition. Notably, our study revealed Mdm2 as a significant negative regulator of 2CLCs, as perturbation of Mdm2 resulted in a higher proportion of 2CLCs. Mdm2 appears to influence cell fate through its impact on cell cycle progression and H3K27me3 epigenetic modifications. In summary, the results of our CRISPR/Cas9 screen have uncovered several genes with distinct functions in regulating totipotency and pluripotency at various levels, offering a valuable resource for potential targets in future molecular studies.

The Roles of GDF-9, BMP-15, BMP-4 and EMMPRIN in Folliculogenesis and In Vitro Fertilization.

Growth differentiation factor 9 (GDF-9) contributes to early ovarian development and oocyte survival. Higher concentrations of GDF-9 in follicular fluid (FF) are associated with oocyte nuclear maturation and optimal embryo development. In in vitro fertilization (IVF), GDF-9 affects the ability of the oocyte to fertilize and subsequent embryonic development. Bone morphogenetic protein 15 (BMP-15) is involved in the regulation of ovarian function and affects oocyte development. During IVF, BMP-15 contributes to the formation of competent blastocysts. BMP-15 may play a role in embryo implantation by affecting endometrial receptivity. Bone morphogenetic protein 4 (BMP-4) is involved in the regulation of follicle growth and development and affects granulosa cell (GC) differentiation. In relation to IVF, BMP-4 is important for embryonic development, influences cell fate and differentiation, and plays a role in facilitating embryo-endometrial interactions during the implantation process. Extracellular matrix metalloproteinase inducer (EMMPRIN) is associated with ovulation and follicle rupture, promotes the release of mature eggs, and affects the modification of the extracellular matrix of the follicular environment. In IVF, EMMPRIN is involved in embryo implantation by modulating the adhesive properties of endometrial cells and promotes trophoblastic invasion, which is essential for pregnancy to occur. The purpose of the current article is to review the studies and recent findings of GDF-9, BMP-15, BMP-4 and EMMPRIN as fundamental factors in normal follicular development and in vitro fertilization.

A nuclear architecture screen in Drosophila identifies Stonewall as a link between chromatin position at the nuclear periphery and germline stem cell fate.

The association of genomic loci to the nuclear periphery is proposed to facilitate cell type-specific gene repression and influence cell fate decisions. However, the interplay between gene position and expression remains incompletely understood, in part because the proteins that position genomic loci at the nuclear periphery remain unidentified. Here, we used an Oligopaint-based HiDRO screen targeting ∼1000 genes to discover novel regulators of nuclear architecture in Drosophila cells. We identified the heterochromatin-associated protein Stonewall (Stwl) as a factor promoting perinuclear chromatin positioning. In female germline stem cells (GSCs), Stwl binds and positions chromatin loci, including GSC differentiation genes, at the nuclear periphery. Strikingly, Stwl-dependent perinuclear positioning is associated with transcriptional repression, highlighting a likely mechanism for Stwl's known role in GSC maintenance and ovary homeostasis. Thus, our study identifies perinuclear anchors in Drosophila and demonstrates the importance of gene repression at the nuclear periphery for cell fate.

Phase separation provides a mechanism to drive phenotype switching.

Phenotypic switching plays a crucial role in cell fate determination across various organisms. Recent experimental findings highlight the significance of protein compartmentalization via liquid-liquid phase separation in influencing such decisions. However, the precise mechanism through which phase separation regulates phenotypic switching remains elusive. To investigate this, we established a mathematical model that couples a phase separation process and a gene expression process with feedback. We used the chemical master equation theory and mean-field approximation to study the effects of phase separation on the gene expression products. We found that phase separation can cause bistability and bimodality. Furthermore, phase separation can control the bistable properties of the system, such as bifurcation points and bistable ranges. On the other hand, in stochastic dynamics, the droplet phase exhibits double peaks within a more extensive phase separation threshold range than the dilute phase, indicating the pivotal role of the droplet phase in cell fate decisions. These findings propose an alternative mechanism that influences cell fate decisions through the phase separation process. As phase separation is increasingly discovered in gene regulatory networks, related modeling research can help build biomolecular systems with desired properties and offer insights into explaining cell fate decisions.

The Hippo signalling pathway in bone homeostasis: Under the regulation of mechanics and aging.

The Hippo signalling pathway is a conserved kinase cascade that orchestrates diverse cellular processes, such as proliferation, apoptosis, lineage commitment and stemness. With the onset of society ages, research on skeletal aging-mechanics-bone homeostasis has exploded. In recent years, aging and mechanical force in the skeletal system have gained groundbreaking research progress. Under the regulation of mechanics and aging, the Hippo signalling pathway has a crucial role in the development and homeostasis of bone. We synthesize the current knowledge on the role of the Hippo signalling pathway, particularly its downstream effectors yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ), in bone homeostasis. We discuss the regulation of the lineage specification and function of different skeletal cell types by the Hippo signalling pathway. The interactions of the Hippo signalling pathway with other pathways, such as Wnt, transforming growth factor beta and nuclear factor kappa-B, are also mentioned because of their importance for modulating bone homeostasis. Furthermore, YAP/TAZ have been extensively studied as mechanotransducers. Due to space limitations, we focus on reviewing how mechanical forces and aging influence cell fate, communications and homeostasis through a dysregulated Hippo signalling pathway.

Quantifying how TCR sequence influences cell fate commitment in chronic LCMV infection

Abstract Repetitive T cell receptor (TCR) engagement on CD8 T cells during chronic infection is a critical driver of the dysfunctional state termed exhaustion. These exhausted cells are characterized by additional heterogeneity including a memory-like progenitor cell (Tpro) that continuously gives rise to either non-cytolytic exhausted cells (Texh) or cytotoxic effector cells (Teff). While we and others have shown that TCR avidity influence cell fate commitment to Texh or Teff, it is not certain if TCR sequence features influence this fate choice. In this study, we identify how TCR V(D)J gene recombination influences T cell differentiation at the single-cell resolution. To investigate this, we performed single-cell resolution TCR sequencing (scTCR-seq) on GP33+ tetramer sorted cells within lymphocytic choriomeningitis virus (LCMV) Clone 13 model of chronic infection across 7 different mice. Utilizing TCRdist and Clonotype Neighbor Graph Analysis (CoNGA), we construct correlations between gene expression and TCR features. We find that both chain usage and cdr3 motifs correlate to effector or exhausted cell fate commitment across these different mice. Overall, our results suggest that TCR gene rearrangement is critical not only for antigen specificity, but also determining CD8 T cell phenotypic outcomes during chronic viral infection.

Molecularly Imprinted Macroporous Hydrogel Promotes Bone Regeneration via Osteogenic Induction and Osteoclastic Inhibition.

Macroporous hydrogels offer physical supportive spaces and bio-instructive environment for the seeded cells, where cell-scaffold interactions directly influence cell fates and subsequently affect tissue regeneration post-implantation. Effectively modifying bioactive motifs at the inner pore surface provides appropriate niches for cell-scaffold interactions. A molecular imprinting method and sacrificial templates are introduced to prepare inner pore surface modification in the macroporous hydrogels. In detail, acrylated bisphosphonates (Ac-BPs) chelating to templates (CaCO3 particles) are anchored on the inner pore surface of the methacrylated gelatin (GelMA)-methacrylated hyaluronic acid (HAMA)-poly (ethylene glycol) diacrylate (PEGDA) macroporous hydrogel (GHP) to form a functional hydrogel scaffold (GHP-int-BP). GHP-int-BP, but not GHP, effectively crafts artificial cell niches to substantially alter cell fates, including osteogenic induction and osteoclastic inhibition, and promote in situ bone regeneration. These findings highlight that molecular imprinting on the inner pore surface in the hydrogel efficiently creates orthogonally additive bio-instructive scaffolds for bone regeneration.

The Odds of Protein Translation Control Under Stress.

Physical or chemical stress is commonly known to inhibit protein translation at the cellular level. Since the process of protein translation requires catalysis by a multi-component machinery containing eukaryotic initiation factors (eIFs) and ribosomes in a sequence of reactions, how the process fails to proceed and whether certain genes can escape such blockade have provoked research efforts. Lines of evidence have demonstrated that phosphorylation of eIF4E or dephosphorylation of 4E-binding proteins (4E-BPs) prevents the formation of the eukaryotic translation initiation factor 4F (eIF4F) complex, whereas phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2α) due to activation of heme-regulated inhibitor (HRI), general control nonderepressible 2 (GCN2), protein kinase RNA-like endoplasmic reticulum kinase (PERK), or protein kinase R (PKR) by a diverse array of stressors prevents eIF2-GTP-tRNAiMet ternary complex assembly. These signal the abandonment of translation initiation via 5'-7-methylguanine (m7G) cap recognition by eIF4E. Stress can promote cleavage of tRNAs, impediment of rRNA processing, changes in the epitranscriptomic landscape, ribosome stalling or collision, activation of ribosomal surveillance systems, and assembly of the stress granules. Although these events contribute to the general inhibition of protein translation, a few proteins can bypass such negativity and become translated selectively. Such selective protein translation is primarily m7G cap independent through the integrated stress response or Internal Ribosomal Entry Site (IRES). The newly synthesized proteins often influence cell fate, facilitate cell survival, and build endogenous defense. Insights into the general inhibition of protein translation and selective translation of specific proteins will advance our understanding of the etiology or progression of human diseases involving cellular stress from viral infection or inflammation to myocardial infarction, stroke, or neurodegenerative disease. Antioxid. Redox Signal. 40, 943-947.

An AGO10:miR165/6 module regulates meristem activity and xylem development in the Arabidopsis root.

The RNA-silencing effector ARGONAUTE10 influences cell fate in plant shoot and floral meristems. ARGONAUTE10 also accumulates in the root apical meristem (RAM), yet its function(s) therein remain elusive. Here, we show that ARGONAUTE10 is expressed in the root cell initials where it controls overall RAM activity and length. ARGONAUTE10 is also expressed in the stele, where post-transcriptional regulation confines it to the root tip's pro-vascular region. There, variations in ARGONAUTE10 levels modulate metaxylem-vs-protoxylem specification. Both ARGONAUTE10 functions entail its selective, high-affinity binding to mobile miR165/166 transcribed in the neighboring endodermis. ARGONAUTE10-bound miR165/166 is degraded, likely via SMALL-RNA-DEGRADING-NUCLEASES1/2, thus reducing miR165/166 ability to silence, via ARGONAUTE1, the transcripts of cell fate-influencing transcription factors. These include PHABULOSA (PHB), which controls meristem activity in the initials and xylem differentiation in the pro-vasculature. During early germination, PHB transcription increases while dynamic, spatially-restricted transcriptional and post-transcriptional mechanisms reduce and confine ARGONAUTE10 accumulation to the provascular cells surrounding the newly-forming xylem axis. Adequate miR165/166 concentrations are thereby channeled along the ARGONAUTE10-deficient yet ARGONAUTE1-proficient axis. Consequently, inversely-correlated miR165/166 and PHB gradients form preferentially along the axis despite ubiquitous PHB transcription and widespread miR165/166 delivery inside the whole vascular cylinder.

Abstract 5630: Targeting the LSD1/ADNP axis as an effective pro-differentiating strategy against acute myeloid leukemia AML

Abstract Acute Myeloid Leukemia (AML) represents a diverse category of blood cancers marked by the clonal proliferation of atypical myeloid precursor cells within the bone marrow. Lysine Specific Demethylase 1 (LSD1), an epigenetic regulator, exhibits elevated expression in AML. Consequently, inhibiting LSD1 has emerged as a promising therapeutic approach for addressing blood and bone marrow cancers. While initial emphasis centered on LSD1's enzymatic inhibition, compelling evidence highlights its pivotal role as a scaffolding protein, orchestrating transcriptional and chromatin remodeling complexes that control cellular differentiation and proliferation. However, our understanding of the precise mechanisms governing these complexes remains limited, necessitating further investigation. The K562 erythroleukemia cell line has served as a prominent model for investigating the molecular factors influencing cell fate determination. In response to specific cues, these cells exhibit a bi-potential capacity, mirroring the behavior of normal hematopoietic megakaryocyte/erythrocyte progenitors (MEP). Notably, when LSD1 is either depleted or inhibited, the erythroid differentiation of K562 cells is hindered, even when exposed to various pro-differentiating triggers, including the BCR-ABL inhibitor Imatinib. In order to gain deeper insights and identify potential new protein partners involved in the K562 differentiation process that interact with LSD1, we employed the erythroleukemic K562 cell model. Using unbiased, proteome-wide proximity labeling we discovered that LSD1 serves as a scaffold for recruitment of the ChAHP complex, comprised of ADNP, CBX3, and CHD4. The ChAHP complex serves fundamental roles in chromatin remodeling, RNA splicing, and transcriptional control. We confirmed these proximity relationships by immunoblotting biotinylated proteins generated in situ by the promiscuous biotin ligase, (BirA*) when anchored to LSD1. We show that depleting ADNP induces spontaneous erythroid differentiation in K562 erythroleukemia cells, which is augmented by BCR-ABL inhibitor Imatinib treatment. ADNP-deficient K562 cells exhibited accelerated erythroid differentiation, as evidenced by a four-fold increase in the surface expression of erythroid markers (CD71, CD235a) and a significant upregulation of beta-globin gene cluster markers. These findings collectively suggest an antagonistic functional relationship between ADNP and LSD1, potentially counterbalancing LSD1's role in lineage allocation. Furthermore, we demonstrate that the loss of the key ChAHP component, ADNP, substantially hampers proliferation and increases apoptosis in K562 cells. These results underscore the potential of ADNP/ChAHP as an appealing target to modulate the choice between erythroid and megakaryocytic fates and offer promise as a target for pro-differentiation therapies in AML Citation Format: Mehraju Din Lone, Mohd Sayeed, Alaa Habieb, Praveen Kumar, Michael E. Engel. Targeting the LSD1/ADNP axis as an effective pro-differentiating strategy against acute myeloid leukemia AML [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5630.

Modification of Biodegradable Polymer Nanofibers for Cartilage Tissue Engineering Applications: A Review

Tissue engineering is the use of a combination of cells, engineering and materials methods, and suitable biochemical and physiochemical factors to improve or replace biological functions at the injured site. The designing of a biomaterial that can mimic the three-dimensional tissues in vivo is still challenging. Biodegradable polymers are used for the development of tissue engineering constructs in the form of sponges, films, and macroporous scaffolds, which do not influence cell fate processes such as cell differentiation, migration, and proliferation. Biodegradable polymer nanofibers fabricated by electrospinning have gathered great attention in tissue engineering applications. The electrospun materials have a nanofibrous morphology that is closest to the natural extracellular matrix (ECM). The electrospun material is composed of three-dimensional networks of nanosized fibrous materials that mimic an extracellular matrix such as collagen, elastin, and keratin. These polymers fabricated in the form of fibers in nanosize cause a more favorable microenvironment for cells. We prepared the PLGA/PPG (polylactic-co-glycolic acid/polypropylene glycol) nanofibers by electrospinning technique. PLGA (85:15)/PLGA (75:25) nanofibers are hydrophobic, which can be minimized by the addition of PPG to give better hydrophilicity for cell adhesion for tissue engineering constructs. The morphology of the electrospun fibers of the composite of PLGA and PPG was observed using scanning electron microscopy (SEM). The results proved that the small amount of polypropylene glycol polymer to the polylactic-co-glycolic acid (PLGA 85:15) drastically improves the hydrophilicity of the electrospun nanofibers. The addition of a small amount of hydrophilic polymer to the biodegradable hydrophobic polymer increases the hydrophilic property and can be used for nanofiber-based tissue engineering constructs. In addition, the biomimetic approach for tissue engineering scaffolds for cartilage repair has been discussed.

Bone Endosteal Mimics Regulates Breast Cancer Development and Phenotype.

Bone is a frequent site for metastatic development in various cancer types, including breast cancer, with a grim prognosis due to the distinct bone environment. Despite considerable advances, our understanding of the underlying processes leading to bone metastasis progression remains elusive. Here, we applied a bioactive three-dimensional (3D) model capable of mimicking the endosteal bone microenvironment. MDA-MB-231 and MCF7 breast cancer cells were cultured on the scaffolds, and their behaviors and the effects of the biomaterial on the cells were examined over time. We demonstrated that close interactions between the cells and the biomaterial affect their proliferation rates and the expression of c-Myc, cyclin D, and KI67, leading to cell cycle arrest. Moreover, invasion assays revealed increased invasiveness within this microenvironment. Our findings suggest a dual role for endosteal mimicking signals, influencing cell fate and potentially acting as a double-edged sword, shuttling between cell cycle arrest and more active, aggressive states.

An integral role of mitochondrial function in the pathophysiology of preeclampsia.

Preeclampsia (PE) is associated with high maternal and perinatal morbidity and mortality. The development of effective treatment strategies remains a major challenge due to the limited understanding of the pathogenesis. In this review, we summarize the current understanding of PE research, focusing on the molecular basis of mitochondrial function in normal and PE placentas, and discuss perspectives on future research directions. Mitochondria integrate numerous physiological processes such as energy production, cellular redox homeostasis, mitochondrial dynamics, and mitophagy, a selective autophagic clearance of damaged or dysfunctional mitochondria. Normal placental mitochondria have evolved innovative survival strategies to cope with uncertain environments (e.g., hypoxia and nutrient starvation). Cytotrophoblasts, extravillous trophoblast cells, and syncytiotrophoblasts all have distinct mitochondrial morphology and function. Recent advances in molecular studies on the spatial and temporal changes in normal mitochondrial function are providing valuable insight into PE pathogenesis. In PE placentas, hypoxia-mediated mitochondrial fission may induce activation of mitophagy machinery, leading to increased mitochondrial fragmentation and placental tissue damage over time. Repair mechanisms in mitochondrial function restore placental function, but disruption of compensatory mechanisms can induce apoptotic death of trophoblast cells. Additionally, molecular markers associated with repair or compensatory mechanisms that may influence the development and progression of PE are beginning to be identified. However, contradictory results have been obtained regarding some of the molecules that control mitochondrial biogenesis, dynamics, and mitophagy in PE placentas. In conclusion, understanding how the mitochondrial morphology and function influence cell fate decisions of trophoblast cells is an important issue in normal as well as pathological placentation biology. Research focusing on mitochondrial function will become increasingly important for elucidating the pathogenesis and effective treatment strategies of PE.