Artificial Stem Research Articles

Evaluation of F2 Mapping Population for Stem Rot Tolerance in Tossa Jute (Corchorus olitorius)

Present investigation was undertaken at ICAR-CRIJAF, Barrackpore, West Bengal, India during summer season (Apr–July) of 2020 to identify the jute breeding lines resistant to stem rot which is one of the major problems in jute production. The identified resistant and susceptible jute accessions (RS-6 and OIJ-272, respectively) were crossed to develop a mapping population for the disease. The resultant F2 population comprising 125 plants was screened for resistance to stem rot disease caused by Macrophomina phaseolina following artificial inoculation. The progress of infection was measured as the length of the infected stem portion (i.e., lesion length in cm) after 7, 14 and 21 days of inoculation (time replication). After stem inoculation investigation indicated that in the F2 population of the cross OIJ-272×RS-6, only 14 plants (PL-100, PL-40, PL-99, PL-33, PL-89, PL-119, PL-1, PL-43, PL-118, PL-121, PL-6, PL-11, PL-55 and PL-86) were found moderately resistant (lesion length 2.0–3.0 cm). In contrast, 10 plants (PL-4, PL-31, PL-19, PL-27, PL-3, PL-50, PL-18, PL-26, PL-47, PL-51) were found highly susceptible (lesion length >5.0 cm). The remaining 101 plants exhibited moderate susceptible symptoms. While the parent OIJ-272 exhibited high susceptibility to stem rot with an average lesion length of 5.53 cm, the parent RS-6 exhibited moderate resistant reaction with an average lesion length of 2.30 cm. Because of good resistance under artificial stem inoculation of this fungi, these 14 F2 plants of the cross can be further exploited for a resistance breeding programme against this deadly disease.

Using artificial intelligence to predict students’ STEM attitudes: an adaptive neural-network-based fuzzy logic model

ABSTRACT Numerous artificial intelligence methods have lately been applied in education. This study proposes an Adaptive Neural-network-based Fuzzy Logic (ANFIS) model combining fuzzy logic and artificial neural networks for predicting students' STEM attitudes. The inputs of the research were determined as grade levels and academic achievement scores, and the output was determined as STEM attitudes. The hybrid optimisation method trained the fuzzy inference system (FIS) to recognise the more effective ANFIS model. Afterward, the effects of the input variables on the output variable were examined with statistical techniques. Finally, the students' artificial and real STEM attitude scores were compared. 600 middle school students participated in the study, and data were gathered using a Personal Information Form and STEM Attitude Scale. The study revealed a significant positive correlation (r = 0.298; p = 0.000) between the generated ANFIS scores and real scores, the real and artificial scores didn't indicate a statistically significant difference. Therefore, the results obtained through ANFIS correctly predict students' STEM attitude scores. The grade level and academic achievement variables showed statistically significant differences in STEM attitudes. This study is a concrete example as it shows that it is possible to know some characteristics of students using artificial intelligence.

Classes of Stem Cells: From Biology to Engineering.

The majority of adult tissues are limited in self-repair and regeneration due to their poor intrinsic regenerative capacity. It is widely recognized that stem cells are present in almost all adult tissues, but the natural regeneration in adult mammals is not sufficient to recover function after injury or disease. Historically, 3 classes of stem cells have been defined: embryonic stem cells (ESCs), adult mesenchymal stem cells (MSCs), and induced pluripotent stem cells (iPSCs). Here, we have defined a fourth fully engineered class: the synthetic artificial stem cell (SASC). This review aims to discuss the applications of these stem cell classes in musculoskeletal regenerative engineering. We screened articles in PubMed and bibliographic search using a combination of keywords. Relevant and high-cited articles were chosen for inclusion in this narrative review. In this review, we discuss the different classes of stem cells that are biologically derived (ESCs and MSCs) or semi-engineered/engineered (iPSCs, SASC). We also discuss the applications of these stem cell classes in musculoskeletal regenerative engineering. We further summarize the advantages and disadvantages of using each of the classes and how they impact the clinical translation of these therapies. Each class of stem cells has advantages and disadvantages in preclinical and clinical settings. We also propose the engineered SASC class as a potentially disease-modifying therapy that harnesses the paracrine action of biologically derived stem cells to mimic regenerative potential. The majority of adult tissues are limited in self-repair and regeneration, even though stem cells are present in almost all adult tissues. Historically, 3 classes of stem cells have been defined: embryonic stem cells (ESCs), adult mesenchymal stem cells (MSCs), and induced pluripotent stem cells (iPSCs). Here, we have defined a fourth, fully engineered class: the synthetic artificial stem cell (SASC). In this review, we discuss the applications of each of these stem cell classes in musculoskeletal regenerative engineering. We further summarize the advantages and disadvantages of using each of these classes and how they impact the clinical translation of these therapies.

Interfacial-Crystallization-Constructed Fractal Nanofiber-Based Bio-Platforms Enable Highly Effective Culture of Three-Dimensional Stem Cell Spheroids.

Artificial cell spheroids are gaining importance in tissue engineering and regenerative medicine fields. Biomimetic construction of stem cell spheroids is nevertheless challenging, and bioplatforms permitting controllable and high-efficient fabrication of functional stem cell spheroids are needed. Here, a fractal nanofiber-based bioplatform is developed based on a tunable interfacial-induced crystallization approach, allowing a programmed culture of artificial stem cell spheroids under an ultralow cell seeding density. Specifically, starting with the nanofibers of poly(L-lactide) (PLLA) and gelatin (PmGn), an interfacial growth of PLLA nanocrystals is subsequently performed to construct the fractal nanofiber-based biotemplates (C-PmGn). Cell experiments with human dental pulp stem cells (hDPSCs) demonstrate that the fractal C-PmGn could effectively decrease cell-matrix interactions, thus facilitating spontaneous cell spheroid formation even under a low cell seeding density (1 × 104 cells/cm2). Nanotopological properties of the C-PmGn bioplatform can be tuned by adjusting the fractal degree, thus enabling its suitability for the 3D culture of diverse hDPSC spheroids. Such a strategy provides a relatively simple and low-cost option for formation, expansion, and utility of stem cell spheroids. It offers another promising pathway to advance the development of stem cell therapies.

The regulation of tendon stem cell distribution, morphology, and gene expression by the modulus of microfibers

The mechanical properties of a stem cell culture substrate significantly impact cell adhesion, survival, migration, proliferation, and differentiation in vitro. A major challenge in engineering artificial stem cell substrate is to properly identify the relevant physical features of native stem cell niches, which are likely different for each stem cell type. The behavior of tendon stem cells has potentially significant implications for tendon repair. Here, microfiber scaffolds with various modulus of elasticity are fabricated by near-field electrospinning, and their regulating effects on the in vitro behavior of tendon stem cells (TSCs) are discussed in this study. The number of pseudopodia shows a biphasic relationship with the modulus of scaffold. The proliferation, polarization ratio and alignment degree along the fibers of the TSCs increase with the increase of fiber modulus. TSCs cultured on the scaffold with moderate modulus (1429 MPa) show the upregulation of tendon-specific genes (Col-I, Tnmd, SCX and TNCF). These microfiber scaffolds provide great opportunities to modulate TSCs behavior at the micrometer scales. In conclusion, this study provides an instructive mechanical microenvironment for TSCs behaviors and may lead to the development of desirable engineered artificial stem cell substrate for tendon healing.

A modified and effective stem inoculation technique for artificial screening against Sclerotinia sclerotiorum in mustard

AbstractSclerotinia stem rot (SR) disease emerged as a potential threat in most mustard‐growing regions globally. Sclerotinia sclerotiorum, a necrotrophic pathogen, causes considerable damage to the crop under congenial environments. The sclerotia even under adverse conditions can survive up to 5 years in the soil. The use of resistant sources is the only mean to combat the pathogen. The development of an effective inoculation technique can facilitate the identification of new sources of resistance rapidly. Investigations on resistant sources using Potato Dextrose Agar (PDA) medium for artificial stem inoculation are ongoing under the All India Coordinated Research Project (AICRP) on rapeseed‐mustard for many years but no resistant sources could been identified. In the present study, two non‐injury stem inoculation techniques using sorghum grains and PDA medium as a basal medium were tested on 11 brassica entries for up to three consecutive years. Results revealed that sorghum grain‐based inoculum was found efficient for disease development and lesion formation in brassica entries compared with PDA‐based inoculum. Among the entries, a maximum disease incidence of 42.3% was recorded in entry DRMR 5206 followed by DRMRSJ‐20, DRMRSJ‐22 and DRMR 2017‐8 with 42.1%, 41.8% and 41.3% SR incidence, respectively. In PDA disc inoculation maximum SR incidence of 30.8% was observed in DRMRSJ‐26 followed by DRMR 5206, DRMRSJ‐25 and DRMRSJ‐2017‐18 with 27.5%–24.9%, respectively. Lesion length was more in entries inoculated with fungal mycelium multiplied on sorghum grains compared with the PDA disc inoculation method. The statistical analysis and results of p‐value (<.00001) showed a significant difference between tested methodologies. Thus, the sorghum grain‐based inoculation technique is an appropriate, economic and effective non‐injury inoculation technique for artificial screening against S. sclerotiorum in the mustard crop. This technique can be used to screen a large number of brassica entries more efficiently with less labour and time.

Bioprinted Notch ligand to function as stem cell niche improves muscle regeneration in dystrophic muscle.

299In Duchenne muscular dystrophy, dystrophic muscle phenotypes are closely associated with the exhaustion of muscle stem cells. Transplantation of muscle stem cells has been widely studied for improving muscle regeneration, but poor cell survival and self-renewal, rapid loss of stemness, and limited dispersion of grafted cells following transplantation have collectively hindered the overall success of this strategy. Optimized mechanisms for maintaining and improving stem cell function are naturally present in the microenvironment of the stem cell niche in healthy muscles. Therefore, one logical strategy toward improving stem cell function and efficiency of stem cell transplantation in diseased muscles would be the establishment of a microenvironment mimicking some key aspects of healthy native stem cell niches. Here, we applied inkjet-based bioprinting technology to engineer a mimicked artificial stem cell niche in dystrophic muscle, comprising stem cell niche regulating factors (Notch activator DLL1) bioprinted onto 3D DermaMatrix construct. The recombinant DLL1 protein, DLL1 (mouse): Fc (human) (rec), was applied here as the Notch activator. Bioprinted DermaMatrix construct was seeded with muscle stem cells in vitro, and increased stem cell maintenance and repressed myogenic differentiation process was observed. DLL1 bioprinted DermaMatrix construct was then engrafted into dystrophic muscle of mdx/scid mice, and the improved cell engraftment and progression of muscle regeneration was observed 10 days after engraftment. Our results demonstrated that bioprinting of Notch activator within 3D construct can be applied to serve as muscle stem cell niche and improve the efficacy of muscle stem cell transplantation in diseased muscle.

Impact of freeze-thaw-induced pit aspiration on stem water transport in the subalpine conifer Abies veitchii.

During winter, subalpine conifers experience frequent freeze-thaw cycles in stem xylem that may cause embolism and pit aspiration due to increased water volume during the sap to ice transition. This study examined the occurrence and ecological impacts of a combination of freeze-thaw-induced pit aspiration and embolism triggered by natural and artificial stem freezing. In subalpine Veitch's fir (Abies veitchii) trees, the fraction of closed pits and embolized tracheids as well as conductivity losses were measured to examine pit aspiration and its effects. When trees incurred mild drought stress in February and early March, 70%-80% of stem conductivity was lost. Cryo-scanning electron microscopy indicated <20% embolized tracheids but ∼90% closed pits. Severe drought stress in late March caused 96% ± 1.2% (mean ± standard error) loss of stem conductivity, while the fraction of embolized tracheids increased to 64% ± 6.6%, and aspirated pit fraction decreased to 23% ± 5.6%. Experimental freeze-thaw cycles also increased pit aspiration from 7.1% ± 0.89% to 49% ± 10%, and the fraction of closed pits was positively correlated to the percent loss of stem hydraulic conductivity. The results indicated that freezing-induced pit aspiration is an important factor for stem xylem dysfunction under mild drought, and upon severe drought in winter; stem water transport is predominantly inhibited by xylem embolism.

Artificial stem cells mediated inflammation-tropic delivery of antiviral drugs for pneumonia treatment

BackgroundCytomegalovirus (CMV) pneumonia is a major cause of morbidity and mortality in immunodeficiency individuals, including transplant recipients and Acquired Immune Deficiency Syndrome patients. Antiviral drugs ganciclovir (GCV) and phosphonoformate (PFA) are first-line agents for pneumonia caused by herpesvirus infection. However, the therapy suffers from various limitations such as low efficiency, drug resistance, toxicity, and lack of specificity.MethodsThe antiviral drugs GCV and PFA were loaded into the pH-responsive nanoparticles fabricated by poly(lactic-co-glycolic acid) (PLGA) and 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP), and further coated with cell membranes derived from bone marrow mesenchymal stem cells to form artificial stem cells, namely MPDGP. We evaluated the viral suppression effects of MPDGP in vitro and in vivo.ResultsMPDGP showed significant inflammation tropism and efficient suppression of viral replication and virus infection-associated inflammation in the CMV-induced pneumonia model. The synergistic effects of the combination of viral DNA elongation inhibitor GCV and viral DNA polymerase inhibitor PFA on suppressing the inflammation efficiently.ConclusionThe present study develops a novel therapeutic intervention using artificial stem cells to deliver antiviral drugs at inflammatory sites, which shows great potential for the targeted treatment of pneumonia. To our best knowledge, we are the first to fabricate this kind of artificial stem cell to deliver antiviral drugs for pneumonia treatment.Graphical

Fabrication of Tβ4-Exosome-releasing artificial stem cells for myocardial infarction therapy by improving coronary collateralization

Currently, stem cell transplantations in cardiac repair are limited owing to disadvantages, such as immunological rejection and poor cell viability. Although direct injection of exosomes can have a curative effect similar to that of stem cell transplantation, high clearance hinders its application in clinical practice. Previous reports suggested that induction of coronary collateralization can be a desired method of adjunctive therapy for someone who had missed the optimal operation time to attenuate myocardial ischemia. In this study, to mimic the paracrine and biological activity of stem cells, we developed artificial stem cells that can continuously release Tβ4-exosomes (Tβ4-ASCs) by encapsulating specific exosomes within microspheres using microfluidics technology. The results show that Tβ4-ASCs can greatly promote coronary collateralization in the periphery of the myocardial infarcted area, and its therapeutic effect is superior to that of directly injecting the exosomes. In addition, to better understand how it works, we demonstrated that the Tβ4-ASC-derived exosomes can enhance the angiogenic capacity of coronary endothelial cells (CAECs) via the miR-17-5p/PHD3/Hif-1α pathway. In brief, as artificial stem cells, Tβ4-ASCs can constantly release functional exosomes and stimulate the formation of collateral circulation after myocardial infarction, providing a feasible and alternative method for clinical revascularization.

The synthetic artificial stem cell (SASC): Shifting the paradigm of cell therapy in regenerative engineering

Stem cells are of great interest in tissue regeneration due to their ability to modulate the local microenvironment by secreting bioactive factors (collectively, secretome). However, secretome delivery through conditioned media still requires time-consuming cell isolation and maintenance and also may contain factors antagonistic to targeted tissue regeneration. We have therefore engineered a synthetic artificial stem cell (SASC) system which mimics the paracrine effect of the stem cell secretome and provides tailorability of the composition for targeted tissue regeneration. We report the first of many applications of the SASC system we have formulated to treat osteoarthritis (OA). Choosing growth factors important to chondrogenesis and encapsulating respective recombinant proteins in poly (lactic-coglycolic acid) 85:15 (PLGA) we fabricated the SASC system. We compared the antiinflammatory and chondroprotective effects of SASC to that of adipose-derived stem cells (ADSCs) using invitro interleukin 1B-induced and invivo collagenase-induced osteoarthritis rodent models. We have designed SASC as an injectable therapy with controlled release of the formulated secretome. In vitro, SASC showed significant antiinflammatory and chondroprotective effects as seen by the up-regulation of SOX9 and reduction of nitric oxide, ADAMTS5, and PRG4 genes compared to ADSCs. In vivo, treatment with SASC and ADSCs significantly attenuated cartilage degeneration and improved the biomechanical properties of the articular cartilage in comparison to OA control. This SASC system demonstrates the feasibility of developing a completely synthetic, tailorable stem cell secretome which reinforces the possibility of developing a new therapeutic strategy that provides better control over targeted tissue engineering applications.

Processing Point Clouds Using Simulated Physical Processes as Replacements of Conventional Mathematically Based Procedures: A Theoretical Virtual Measurement for Stem Volume

Conventional mathematically based procedures in forest data processing have some problems, such as deviations between the natural tree and the tree described using mathematical expressions, and manual selection of equations and parameters. These problems are rooted at the algorithmic level. Our solution for these problems was to process raw data using simulated physical processes as replacements of conventional mathematically based procedures. In this mechanism, we treated the data points as solid objects and formed virtual trees. Afterward, the tree parameters were obtained by the external physical detection, i.e., computational virtual measurement (CVM). CVM simulated the physical behavior of measurement instruments in reality to measure virtual trees. Namely, the CVM process was a pure (simulated) physical process. In order to verify our assumption of CVM, we developed the virtual water displacement (VWD) application. VWD could extract stem volume from an artificial stem (consisted of 2000 points) by simulating the physical scenario of a water displacement method. Compared to conventional mathematically based methods, VWD removed the need to predefine the shape of the stem and minimized human interference. That was because VWD utilized the natural contours of the stem through the interaction between the point cloud and the virtual water molecules. The results showed that the stem volume measured using VWD was 29,636 cm3 (overestimation at 6.0%), where the true volume was 27,946 cm3. The overall feasibility of CVM was proven by the successful development of VWD. Meanwhile, technical experiences, current limitations, and potential solutions were discussed. We considered CVM as a generic method that focuses the objectivity at the algorithmic level, which will become a noteworthy development direction in the field of forest data processing in the future.

Design Artificial Stem Cell Nests for Stem Cell Niche in a Microfluidic Petri Dish Programmed by a Cell Phone

Adv. Mater. Technol. 2021, 6, 2100045 DOI: 10.1002/admt.202100045 In the originally published article, six instances of data published in this manuscript were misreported by a magnitude of ten. In the abstract and Section 2.6, titled The Embryonic Stem Cell (H9)-Cancer Cell (A549) Auto Coculture via a Programable Microfluidic Petri Dish, the values (3.57 ± 0.52) × 105, (11.67 ± 1.33) × 105, and (53.34 ± 8.37) × 105, should be reported as (3.57 ± 0.52) × 104, (11.67 ± 1.33) × 104, and (53.34 ± 8.37) × 104, respectively. The authors apologize for any confusion this may have cause.

Biofabrication of Artificial Stem Cell Niches in the Anterior Ocular Segment.

The anterior segment of the eye is a complex set of structures that collectively act to maintain the integrity of the globe and direct light towards the posteriorly located retina. The eye is exposed to numerous physical and environmental insults such as infection, UV radiation, physical or chemical injuries. Loss of transparency to the cornea or lens (cataract) and dysfunctional regulation of intra ocular pressure (glaucoma) are leading causes of worldwide blindness. Whilst traditional therapeutic approaches can improve vision, their effect often fails to control the multiple pathological events that lead to long-term vision loss. Regenerative medicine approaches in the eye have already had success with ocular stem cell therapy and ex vivo production of cornea and conjunctival tissue for transplant recovering patients’ vision. However, advancements are required to increase the efficacy of these as well as develop other ocular cell therapies. One of the most important challenges that determines the success of regenerative approaches is the preservation of the stem cell properties during expansion culture in vitro. To achieve this, the environment must provide the physical, chemical and biological factors that ensure the maintenance of their undifferentiated state, as well as their proliferative capacity. This is likely to be accomplished by replicating the natural stem cell niche in vitro. Due to the complex nature of the cell microenvironment, the creation of such artificial niches requires the use of bioengineering techniques which can replicate the physico-chemical properties and the dynamic cell–extracellular matrix interactions that maintain the stem cell phenotype. This review discusses the progress made in the replication of stem cell niches from the anterior ocular segment by using bioengineering approaches and their therapeutic implications.

Stem Cell Niche Microenvironment: Review.

The cornea comprises a pool of self-regenerating epithelial cells that are crucial to preserving clarity and visibility. Limbal epithelial stem cells (LESCs), which live in a specialized stem cell niche (SCN), are crucial for the survival of the human corneal epithelium. They live at the bottom of the limbal crypts, in a physically enclosed microenvironment with a number of neighboring niche cells. Scientists also simplified features of these diverse microenvironments for more analysis in situ by designing and recreating features of different SCNs. Recent methods for regenerating the corneal epithelium after serious trauma, including burns and allergic assaults, focus mainly on regenerating the LESCs. Mesenchymal stem cells, which can transform into self-renewing and skeletal tissues, hold immense interest for tissue engineering and innovative medicinal exploration. This review summarizes all types of LESCs, identity and location of the human epithelial stem cells (HESCs), reconstruction of LSCN and artificial stem cells for self-renewal.

Encapsulation of murine hematopoietic stem and progenitor cells in a thiol-crosslinked maleimide-functionalized gelatin hydrogel

Biomaterial platforms are an integral part of stem cell biomanufacturing protocols. The collective biophysical, biochemical, and cellular cues of the stem cell niche microenvironment play an important role in regulating stem cell fate decisions. Three-dimensional (3D) culture of stem cells within biomaterials provides a route to present biophysical and biochemical stimuli through cell-matrix interactions and cell-cell interactions via secreted biomolecules. Herein, we describe a maleimide-functionalized gelatin (GelMAL) hydrogel that can be crosslinked via thiol-Michael addition click reaction for the encapsulation of sensitive stem cell populations. The maleimide functional units along the gelatin backbone enables gelation via the addition of a dithiol crosslinker without requiring external stimuli (e.g., UV light, photoinitiator), thereby reducing reactive oxide species generation. Additionally, the versatility of crosslinker selection enables easy insertion of thiol-containing bioactive or bioinert motifs. Hematopoietic stem cells (HSCs) and mesenchymal stem cells (MSCs) were encapsulated in GelMAL, with mechanical properties tuned to mimic the in vivo bone marrow niche. We report the insertion of a cleavable peptide crosslinker that can be degraded by the proteolytic action of Sortase A, a mammalian-inert enzyme. Notably, Sortase A exposure preserves stem cell surface markers, which are an essential metric of hematopoietic activity used in immunophenotyping. This novel GelMAL system enables a route to produce artificial stem cell niches with tunable biophysical properties, intrinsic cell-interaction motifs, and orthogonal addition of bioactive crosslinks. Statement of significanceWe describe a maleimide-functionalized gelatin hydrogel that can be crosslinked via a thiol-maleimide mediated click reaction to form a stable hydrogel without the production of reactive oxygen species typical in light-based crosslinking. The mechanical properties can be tuned to match the in vivo bone marrow microenvironment for hematopoietic stem cell culture. Additionally, we report inclusion of a peptide crosslinker that can be cleaved via the proteolytic action of Sortase A and show that Sortase A exposure does not degrade sensitive surface marker expression patterns. Together, this approach reduces stem cell exposure to reactive oxygen species during hydrogel gelation and enables post-culture quantitative assessment of stem cell phenotype.

A Liar’s Epistemology

AbstractThis methodologically important essay aims to trace a genealogical account of Herbert Simon’s media philosophy and to contest the histories of artificial intelligence that overlook the organizational capacities of computational models. As Simon’s work demonstrates, humans’ subjection to large-scale organizations and divisions of labor is at the heart of artificial intelligence. As such, questions of procedures are key to understanding the power assumed by institutions wielding artificial intelligence. Most media-historical accounts of the development of contemporary artificial intelligence stem from the work of Warren S. McCulloch and Walter Pitts, especially the 1943 essay “A Logical Calculus of the Ideas Immanent in Nervous Activity.” Yet Simon’s revenge is perhaps that reinforcement learning systems adopt his prescriptive approach to algorithmic procedures. Computer scientists criticized Simon for the performative nature of his artificially intelligent systems, mainly for his positivism, but he defended his positivism based on his belief that symbolic computation could stand in for any reality and in fact shape that reality. Simon was not looking to actually re-create human intelligence; he was using coercion, bad faith, and fraud as tactical weapons in the reordering of human decision-making. Artificial intelligence was the perfect medium for his explorations.

Stem Cell Nests: Design Artificial Stem Cell Nests for Stem Cell Niche in a Microfluidic Petri Dish Programmed by a Cell Phone (Adv. Mater. Technol. 6/2021)

Stem Cell Nests: Design Artificial Stem Cell Nests for Stem Cell Niche in a Microfluidic Petri Dish Programmed by a Cell Phone (Adv. Mater. Technol. 6/2021)

Bioengineering Self-Organizing Signaling Centers to Control Embryoid Body Pattern Elaboration.

Multicellular systems possess an intrinsic capacity to autonomously generate nonrandom state distributions or morphologies in a process termed self-organization. Facets of self-organization, such as pattern formation, pattern elaboration, and symmetry breaking, are frequently observed in developing embryos. Artificial stem cell-derived structures including embryoid bodies (EBs), gastruloids, and organoids also demonstrate self-organization, but with a limited capacity compared to their in vivo developmental counterparts. There is a pressing need for better tools to allow user-defined control over self-organization in these stem cell-derived structures. Here, we employ synthetic biology to establish an efficient platform for the generation of self-organizing coaggregates, in which HEK-293 cells overexpressing P-cadherin (Cdh3) spontaneously form cell clusters attached mostly to one or two locations on the exterior of EBs. These Cdh3-expressing HEK cells, when further engineered to produce functional mouse WNT3A, evoke polarized and gradual Wnt/β-catenin pathway activation in EBs during coaggregation cultures. The localized WNT3A provision induces nascent mesoderm specification within regions of the EB close to the Cdh3-Wnt3a-expressing HEK source, resulting in pattern elaboration and symmetry breaking within EBs. This synthetic biology-based approach puts us closer toward engineering synthetic organizers to improve the realism in stem cell-derived structures.

Design Artificial Stem Cell Nests for Stem Cell Niche in a Microfluidic Petri Dish Programmed by a Cell Phone

AbstractThis article describes a technology to transform a petri dish into a microfluidic chip with a stem cell nest for stem cell niche engineering. A permanent magnet sphere is put in a 30 mm petri dish as an oscillator pump (O‐pump). An earphone‐sized actuator outside the petri dish receives the programmed audio signal from an MP3 player or a mobile phone to drive the in‐dish O‐pump for a microflow. There are guiding walls to form a wake area for the cell nest at the dish's center. The cell nest uses the wake to create a stable, ultraslow internal microcirculation flow. The retention half‐life of nanoparticles in the cell nest is 1419.8 ± 1.3 s. By setting the microfluidic program and supplementing five drops of the culture medium outside the cell nest every 2 d, the growth rate of embryonic stem cells in the cell nest during the 8 d automatic culture appears significantly optimized. The single clone area of embryonic stem cells increases from (3.57 ± 0.52) × 105 to (11.67 ± 1.33) × 105 µm2 after 2 d of the automatic culture and advances to (53.34 ± 8.37) × 105 µm2 after 4 d.