Fetal Pig Research Articles

Abstract 15500: Identifying Cardiomyocytes at Specific Cell-Cycle Stages by a New Cell-Cycle-Specific snRNAseq Analytic Method

Background: Deciphering the cardiomyocyte cell cycle is a critical question in studying heart development and regeneration. We already collected the single-nuclei RNA sequencing (snRNAseq) data from fetal pig hearts and from pigs that underwent apical resection on postnatal day (P) 1 (AR P1 ) followed by myocardial infarction (MI) on P28 (MI P28 ); in these hearts, robust cardiomyocyte proliferation was confirmed. Research questions: Although our previous snRNAseq analyses found cardiomyocyte clusters that primed to proliferate, each of these clusters only appeared at one specific time point; furthermore, these clusters still contain a significant amount of non-cycling cell; and thus, we were unable to distinguish between cardiomyocytes in different phases of the cell cycle. Approach: In this report, we designed a new Autoencoder that only utilized 1646 cell-cycle-specific genes to cluster cardiomyocytes and applied the Autoencoder on pig heart GEO datasets number GSE185289. Results: Five cardiomyocyte clusters (pCM1+2, pCM3-pCM6) were identified. Five proliferation markers (AURKB, MKI67, INCENP, CDCA8, and BRCA5) highly co-expressed in pCM1+2; also, the top enriched gene ontologies of pCM1+2 were all related to cell-cycle. PCM1+2 percentages were ~6% in fetal hearts and ~2-3% in hearts from ARP1MIP28 pigs during the two weeks after MI induction but were nearly undetectable in all other experimental groups and at all other time points. We also identified four transcription factors (E2F8, FOXM1, GLI3, and RAD51) that explicitly coexpressed within pCM1. Also, a pseudo-time trajectory was constructed in Fetal cardiomyocyte, which began at pCM3 (G1/S phase, CCND2 localization), passed through pCM2 (S phase, CCNE2 localization), and ended at pCM1 (M phase, CCNB2 localization). Conclusions: Applying the more precise cell-cycle specific Autoencoder, we found three clusters that likely represented cardiomyocytes at three different cell-cycle stages.

The continuous structure of the joint capsule and meniscus in the pig knee.

The knee joint capsules composed of a fibrous layer and a synovial layer. The knee meniscus consists of the superficial network, lamellar layer, tie fibre and circumferential bundles. However, the continuous structure of the knee joint capsule and meniscus has not been reported. Fetal and adult pigs were used to investigate the structural relationship between the stifle joint capsule and meniscus based on the gross anatomy and histological findings. In the gross anatomical examination, the joint capsule appeared to have separated attachments to the meniscus, except for the lower aspect of the popliteal hiatus. Histologically, the lower half of the popliteal hiatus was found to have separated attachments, with vessels running between the attachments of the joint capsules. The synovial layer of the joint capsule continued to the superficial network, and the fibrous layer of the joint capsule continued to the lamellar layer and tie fibres. There were two routes of arterial entry into the meniscus: intracapsular and intercapsular. It appeared that the presence of separated attachments of the joint capsule was necessary to allow the intercapsular route. This study clarified for the first time the routes of feeding vessels entering the meniscus and proposed to call this entry point the meniscus hilum. We consider that this detailed anatomical information is important for understanding the continuation between the joint capsule and the meniscus.

Morphological study of the arterial supply to the menisci in pigs with special reference to creating meniscus injury model.

Some reports have used pigs to establish models of meniscus injury. However, accurate information on the origin, course, and access of the arteries supplying the menisci remains unclear. This information is important to avoid damaging vital arteries when creating the meniscus injury model. In this study, fetal and adult pigs were employed to investigate the arterial supply of the menisci in pigs using gross anatomical and histological methods. Macro-anatomically, the anterior horn, body, and posterior horn of the medial meniscus were found to be supplied by the medial superior genicular artery, medial inferior genicular artery, and posterior middle genicular artery. The anterior and posterior horns of the lateral meniscus were supplied by the cranial tibial recurrent artery and the middle genicular artery, respectively. Anastomosis was observed in some cases, but appeared to be infrequent and too thin to expect the anastomotic branches to provide adequate blood flow. The histological examination showed that the arteries entered the meniscus along the tie-fiber. The access process of the artery was the same irrespective of whether it was in fetal or mature pigs, the medial or lateral meniscus, or the anterior horn or body or posterior horn. The medial inferior genicular artery ran along the medial meniscus in the circumferential direction. Therefore, the clinical longitudinal incision should take into account the characteristics of the vessel course in order to protect the blood vessels from damage. Based on the results of this study, the protocol for creating a pig meniscus injury model should be reconsidered.

Effects of Gestational Hypoxia on PGC1α and Mitochondrial Acetylation in Fetal Guinea Pig Hearts

Chronic intrauterine hypoxia is a significant pregnancy complication impacting fetal heart growth, metabolism, and mitochondrial function, contributing to cardiovascular programming of the offspring. PGC1α (peroxisome proliferator-activated receptor γ co-activator 1α) is the master regulator of mitochondrial biogenesis. We investigated the effects of hypoxia on PGC1α expression following exposure at different gestational ages. Time-mated pregnant guinea pigs were exposed to normoxia (NMX, 21% O2) or hypoxia (HPX, 10.5% O2) at either 25-day (early-onset) or 50-day (late-onset) gestation, and all fetuses were extracted at term (term = ~65-day gestation). Expression of nuclear PGC1α, sirtuin 1 (SIRT1), AMP-activated protein kinase (AMPK), and mitochondrial sirtuin 3 (SIRT3) was measured, along with SIRT3 activity and mitochondrial acetylation of heart ventricles of male and female fetuses. Early-onset hypoxia increased (P<0.05) fetal cardiac nuclear PGC1α and had no effect on mitochondrial acetylation of either growth-restricted males or females. Late-onset hypoxia had either no effect or decreased (P<0.05) PCC1α expression in males and females, respectively, but increased (P<0.05) mitochondrial acetylation in both sexes. Hypoxia had variable effects on expression of SIRT1, AMPK, SIRT3, and SIRT3 activity depending on the sex. The capacity of the fetal heart to respond to hypoxia differs depending on the gestational age of exposure and sex of the fetus. Further, the effects of late-onset hypoxia on fetal heart function impose a greater risk to male than female fetuses, which has implications toward cardiovascular programming effects of the offspring.

Report of an Experiment With a Fetal Ex-Utero Support System in Piglets.

Extreme prematurity remains one of the leading causes of neonatal death. An ex-utero treatment strategy that allows the fetus to develop beyond this period until capable of tolerating the transition to post-natal physiology would significantly impact the quality of care offered for this pre-viable patient population. In this study, we report our experience with an ex-utero support system for fetal pigswith the goal of support and survival for eight hours. Our experiment included two pigs at a gestational age equivalent to a 32-week human fetus. Following ultrasound assessment and delivery via hysterotomy, the fetuses were transferred to a 40 L glass aquarium filled with warmed lactated Ringer's solution and connected to an arteriovenous (AV) circuit that included a centrifugal pump and a pediatric oxygenator.Fetus 1 was successfully cannulated and survived for seven hours (expected maximum duration of eight hours). Fetus 2 died shortly after hysterotomy, secondary to failure at the cannulation stage. Our results suggest that ex-utero support of the premature fetal pig is feasible, contributing to a scarce body of evidence. However, further studies are needed before effectively translating an artificial placenta system into the clinical arena.

RACK1 may participate in placental development at mid-gestation via regulating trophoblast cell proliferation and migration in pigs.

Intrauterine growth restriction (IUGR) is a severe complication in swine production. Placental insufficiency is responsible for inadequate fetal growth, but the specific etiology of placental dysfunction-induced IUGR in pigs remains poorly understood. In this work, placenta samples supplying the lightest weight (LW) and mean weight (MW) pig fetuses in the litter at Day 65 (D65) of gestation were collected, and the relationship between fetal growth and placental morphologies and functions was investigated using histomorphological analysis, RNA sequencing, quantitative polymerase chain reaction, and in vitro experiment in LW and MW placentas. Results showed that the folded structure of the epithelial bilayer of LW placentas followed a poor and incomplete development compared with that of MW placentas. A total of 654 differentially expressed genes (DEGs) were screened out between the LW and MW placentas, and the gene encodes receptor for activated C kinase 1 (RACK1) was found to be downregulated in LW placentas. The DEGs were mainly enriched in translation, ribosome, protein synthesis, and mammalian target of rapamycin (mTOR) signaling pathway according to gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. In vitro experiments indicated that the decreased RACK1 in LW placentas may be involved in abnormal development of placental folds (PFs) by inhibiting the proliferation and migration of porcine trophoblast cells. Taken together, these results revealed that RACK1 may be a vital regulator in the development of PFs via regulating trophoblast cell proliferation and migration in pigs.

Integrated Analysis of DNA Methylation and Gene Expression in Porcine Placental Development.

Proper placental development is crucial for the conceptus to grow and survive, because the placenta is responsible for transporting nutrients and oxygen from the pregnant female to the developing fetus. However, the processes of placental morphogenesis and fold formation remain to be fully elucidated. In this study, we used whole-genome bisulfite sequencing and RNA sequencing to produce a global map of DNA methylation and gene expression changes in placentas from Tibetan pig fetuses 21, 28, and 35 days post-coitus. Substantial changes in morphology and histological structures at the uterine-placental interface were revealed via hematoxylin-eosin staining. Transcriptome analysis identified 3959 differentially expressed genes (DEGs) and revealed the key transcriptional properties in three stages. The DNA methylation level in the gene promoter was negatively correlated with gene expression. We identified a set of differentially methylated regions associated with placental developmental genes and transcription factors. The decrease in DNA methylation level in the promoter was associated with the transcriptional activation of 699 DEGs that were functionally enriched in cell adhesion and migration, extracellular matrix remodeling, and angiogenesis. Our analysis provides a valuable resource for understanding the mechanisms of DNA methylation in placental development. The methylation status of different genomic regions plays a key role in establishing transcriptional patterns from placental morphogenesis to fold formation.

MicroRNA and mRNA sequencing analyses reveal key hepatic metabolic and signaling pathways responsive to maternal undernutrition in full-term fetal pigs

Maternal undernutrition is highly prevalent in developing countries, leading to severe fetus/infant mortality, intrauterine growth restriction, stunting, and severe wasting. However, the potential impairments of maternal undernutrition to metabolic pathways in offspring are not defined completely. In this study, 2 groups of pregnant domestic pigs received nutritionally balanced gestation diets with or without 50% feed intake restriction from 0 to 35 gestation days and 70% from 35 to 114 gestation days. Full-term fetuses were collected via C-section on day 113/114 of gestation. MicroRNA and mRNA deep sequencing were analyzed using the Illumina GAIIx system on fetal liver samples. The mRNA-miRNA correlation and associated signaling pathways were analyzed via CLC Genomics Workbench and Ingenuity Pathway Analysis Software. A total of 1189 and 34 differentially expressed mRNA and miRNAs were identified between full-nutrition (F) and restricted-nutrition (R) groups. The correlation analyses showed that metabolic and signaling pathways such as oxidative phosphorylation, death receptor signaling, neuroinflammation signaling pathway, and estrogen receptor signaling pathways were significantly modified, and the gene modifications in these pathways were associated with the miRNA changes induced by the maternal undernutrition. For example, the upregulated (P<.05) oxidative phosphorylation pathway in R group was validated using RT-qPCR, and the correlational analysis indicated that miR-221, 103, 107, 184, and 4497 correlate with their target genes NDUFA1, NDUFA11, NDUFB10 and NDUFS7 in this pathway. These results provide the framework for further understanding maternal malnutrition's negative impacts on hepatic metabolic pathways via miRNA-mRNA interactions in full-term fetal pigs.

Compensatory mechanisms in response to induced hypothyroidism in the late gestation pig fetus†.

To understand the effect of fetal thyroid gland disruption on development in swine, we evaluated thyroid hormone levels, growth and developmental characteristics, and gene expression associated with thyroid hormone metabolism in late gestation fetuses exposed to methimazole (MMI). Pregnant gilts were given either oral MMI or equivalent sham from gestation day 85-106 (n= 4/group), followed by intensive phenotyping of all fetuses (n= 120). Samples of liver (LVR), kidney (KID), fetal placenta (PLC), and the corresponding maternal endometrium (END) were collected from a subset of fetuses (n= 32). Fetuses exposed to MMI in utero were confirmed hypothyroid, with a significant increase in thyroid gland size, goitrous thyroid histology, and dramatically suppressed thyroid hormone in serum. In dams, no differences in temporal measurements of average daily gain, thyroid hormone, or rectal temperatures relative to controls suggests that MMI had little effect on maternal physiology. However, fetuses from MMI-treated gilts exhibited significant increases in body mass, girth, and vital organ weights, but no differences in crown-rump length or bone measurements suggesting non-allometric growth. The PLC and END showed a compensatory decrease in expression of inactivating deiodinase (DIO3). Similar compensatory gene expression was observed in fetal KID and LVR with a downregulation of all deiodinases (DIO1, DIO2, DIO3). Minor alterations in the expression of thyroid hormone transporters (SLC16A2 and SLC16A10) were observed in PLC, KID, and LVR. Collectively, MMI crosses the PLC of the late gestation pig, resulting in congenital hypothyroidism, alterations in fetal growth, and compensatory responses within the maternal fetal interface.

Characterisation of new animal cell cultures’ sensitivity to &lt;i&gt;Coxsackievirus B5&lt;/i&gt; and &lt;i&gt;Herpes simplex virus‑1&lt;/i&gt;

The increase in the number of cell cultures for virology and biotechnology enhances the chances of a successful response to threats related to outbreaks of well-known and new human infectious diseases. It is a vital task to search for cell cultures sensitive to a wide spectrum of viruses.The aim of the study was to investigate the sensitivity of new diploid animal cell cultures (fibroblasts of a foetal pig’s kidneys and larynx) to Coxsackievirus B5 (CVB5) and Herpes simplex virus-1 (HSV-1).Materials and methods. The cultures of porcine foetal kidney fibroblasts (PFKF) and porcine foetal larynx fibroblasts (PFLF) were derived from a foetus of a healthy pig by mild trypsinisation. The study determined the sensitivity of these new PFKF and PFLF cultures to the above-mentioned viruses by the cytopathic effect (CPE) expressed as a percentage. The infectious activity of CVB5 was studied using real-time polymerase chain reaction (PCR) with the determination of amplification cycle threshold values (Ct); that of HSV-1 was studied using quantitative titration of the virus-containing liquid (VCL). Infectious activity values were expressed as tissue culture 50% infective doses (TCID50).Results. The authors developed diploid PFKF and PFLF cell cultures. PFKF cells demonstrated high sensitivity to CVB5, with a CPE of 87.5±3.3% after passage 3 and a satisfactory concentration of enterovirus RNA in the VCL of 22–24 Ct . The sensitivity of PFKF cells to HSV-1 corresponded to a CPE of 92.1±5.5%. In these cells, the infectious activity of HSV-1 corresponded to 104.25 TCID50/0.2 mL. The experiments with PFLF cells showed low CPE and infectious activity values for both viruses.Conclusions. The study demonstrated high CPE values with the CVB5 (CB5-8100) and HSV-1 (HSV-1/L-2) strains as examples and confirmed the sensitivity of the new diploid PFKF cell culture to these test viruses. Thus, the PFKF cell culture offers potential applications in virology and biotechnology and may be a candidate for testing other strains of CVB5 and HSV-1.

Fetal pig dissection lab with detailed images

Fetal pig dissection lab with detailed images

Exogenous porcine somatotropin administered to late pregnant gilts alters liver and muscle functionalities in pig foetuses

Neonatal maturity depends on the maternal capacity to provide nutrients for foetal growth. This study aimed to investigate the effects of systemic administration of recombinant porcine somatotropin (pST), one of the main regulators of growth and metabolism, to pregnant gilts during late gestation on circulating nutrients and expression levels of genes in liver and skeletal muscle of their 110-day-old foetuses. Gilts received either daily injections of sterile water (control [CTL] group, n = 15) or of 5 mg of pST (pST group, n = 17) from days 90 to 109 of gestation. At day 110 postconceptus, pairs of foetuses (one of small and one of average size within a litter) were selected. Circulating fructose concentrations were greater, but circulating concentrations of urea were lower in pST than in CTL foetuses. Expression levels of genes involved in carbohydrate and lipid metabolism were more affected by pST treatment in liver than in muscle. Hepatic molecular changes suggest an inhibition of energy-consuming processes (glycogen and lipid biosynthesis) and the activation of energy-producing pathway (mitochondrial oxidation) in pST compared to CTL foetuses. Expression levels of some genes involved in intracellular degradation of proteins were greater in the liver of pST foetuses, and combined with lower uremia, this suggests a higher utilisation of protein sources in pST foetuses than in CTL foetuses. In muscle, molecular changes were mainly observed in the IGF-insulin axis. Altogether, pST-treated gilts seem to have a greater ability to support foetal liver development by the reorientation of energy and protein metabolism.

Excitatory and inhibitory neuron imbalance in the intrauterine growth restricted fetal guinea pig brain: Relevance to the developmental origins of schizophrenia and autism.

Neurodevelopmental disorders such as schizophrenia and autism are thought to involve an imbalance of excitatory and inhibitory signaling in the brain. Intrauterine growth restriction (IUGR) is a risk factor for these disorders, with IUGR onset occurring during critical periods of neurodevelopment. The aim of this study was to determine the impact of IUGR on excitatory and inhibitory neurons of the fetal neocortex and hippocampus. Fetal brains (n=2) were first collected from an unoperated pregnant guinea pig at mid-gestation (32days of gestation [dg]; term ∼67dg) to visualize excitatory (Ctip2) and inhibitory (calretinin [CR] and somatostatin [SST]) neurons via immunohistochemistry. Chronic placental insufficiency (CPI) was then induced via radial artery ablation at 30dg in another cohort of pregnant guinea pigs (n=8) to generate IUGR fetuses (52dg; n=8); control fetuses (52dg; n=7) were from sham surgeries with no radial artery ablation. At 32dg, Ctip2- and CR-immunoreactive (IR) cells had populated the cerebral cortex, whereas SST-IR cells had not, suggesting these neurons were yet to complete migration. At 52dg, in IUGR versus control fetuses, there was a reduction in SST-IR cell density in the cerebral cortex (p=.0175) and hilus of the dentate gyrus (p=.0035) but not the striatum (p>.05). There was no difference between groups in the density of Ctip2-IR (cortex) or CR-IR (cortex, hippocampus) neurons (p>0.05). Thus, we propose that an imbalance in inhibitory (SST-IR) and excitatory (Ctip2-IR) neurons in the IUGR fetal guinea pig brain could lead to excitatory/inhibitory dysfunction commonly seen in neurodevelopmental disorders such as autism and schizophrenia.

Abstract 11735: Single-Nucleus RNA Sequencing Analysis Reveals Subpopulation of Endothelial Cells Activation in Hearts of Porcine Double Injury Model

Pigs underwent a double injury model: neonatal day 1 apical resection (AR P1 ) and postnatal day 28 LAD ligation (MI P28 ) can remuscularize the AMI by postnatal day 56 (P56) with little evidence of myocardial scarring, which is accompanied by increased cardiomyocytes (CMs) cell-cycle activity. The vascularization that occurred to support remuscularization has not been studied. Therefore, we analyze the single-nucleus RNA sequencing (snRNA-seq) data collected from the MI-border zone of AR P1 -MI P28 , MI P28 (without AR P1 ), naïve, and fetal pig endothelial cells (ECs) using the Artificial Intelligence autoencoder and cluster analyses. Three clusters of EC were identified. Among them, vascular and lymphatic EC clusters (EC1 and EC2) were presented in all postnatal hearts. Besides expressing vascular EC gene signatures, the remaining cluster, named ‘EC3’, also upregulated Transforming grow factor-beta (TGFβ) and Bone Morphogenetic Proteins (BMP) signaling markers. The signaling indicated EC3 was still under development. EC3 strongly presented in the fetal heart (31% of ECs); then, EC3 proportions decreased as the pig matured and virtually dismissed (&lt;2%) in the naïve heart from P28 to later. Up to 1-week following MI P28 injury, EC3 proportions remained low (&lt;2%) in MI P28 -only hearts; meanwhile, EC3 proportions significantly increased (&gt;7%) in the regenerative AR P1 -MI P28 hearts. Thus, in the AR P1 -MI P28 injured hearts, the subpopulation of EC3 is activated to support remuscularization. Figure. SnRNA-seq analysis identifies a cluster of under-development endothelial cells (EC3). A) UMAP: three EC clusters. B) UMAP: vascular EC marker PLVAP expressesed (calculated using Seurat) in EC1 and EC3. C) UMAP: lymphatic EC marker CCL21 expressesed in EC2. D) Heatmap: TGFβ and BMP signaling upregulated in EC3. C) Bargraph: proportions of EC3 in naïve and injured hearts on postnatal days P28, P30, and P35; P-value and Fold-change (FC) were calculated using Fisher’s exact test.

Detection of microplastics in domestic and fetal pigs’ lung tissue in natural environment: A preliminary study

Microplastics (MPs) are ubiquitous in the environment. However, it is unclear whether MPs are present in mammalian lungs through inhalation, and if so, could be possibly found in fetal tissues. In this study, we aim to determine the presence and characteristics of particles in domestic and fetal pig lung tissue in the natural environment. Specimens from the lungs of domestic pigs (n = 10) and fetal pigs that already died in matrix during vaginal birth from the non-contaminated area (n = 10) were obtained from farmers’ nearby sludge treatment plant. These specimens were compressed between two glass microscope slides, which were examined under polarized light microscopy. In addition, Agilent 8700 LDIR Chemical imaging system (LDIR) was used to determine the quantitative and qualitative characteristics of MPs. According to the polarized light microscope survey of domestic pig lungs, we observed an average of 12 particles/g, which was more than the 6 particles/g observed in fetal pig lungs, which ranged in size from 115.14 μm to 1370.43 μm. All the observed MP particles were fiber in shape. LDIR indicated an average of 180 particles/g of domestic pig lungs, ranging in size from 20.34 μm to 916.36 μm, which was twice as many MPs observed in fetal pig lungs. Furthermore, the compositions of MPs were different between them. LDIR indicated that polyamide (PA) was the most common polymer identified in domestic pig lungs (46.11%), while polycarbonate (PC) was the most common polymer in fetal pig lungs (32.99%). These findings confirmed the presence of MPs in the lung tissue of both domestic and fetal pigs in the natural environment, but the main characteristics differed. This fact indicated the increasing risk of MPs to human respiratory tract is increasing. Further research should be conducted to entirely estimate the specific exposure level on humans and offspring.

Feasibility of MRI Quantification of Myelin Water Fraction in the Fetal Guinea Pig Brain.

Fetal myelination assessment is important for understanding neurodevelopment and neurodegeneration. Myelin water imaging (MWI) quantifies myelin water fraction (MWF), a validated marker for myelin content, and has been used to assess brain myelin in children and neonates. To demonstrate that MWI can quantify MWF in fetal guinea pigs (GPs). Animal model. Nine pregnant, Dunkin-Hartley GPs with 31 fetuses (mean ± standard deviation=60 ± 1.5 days gestation). 3D spoiled gradient echo and balanced steady-state free precession sequences at 3.0 T. MWF maps were reconstructed for maternal and fetal GP brains using the multicomponent driven equilibrium single pulse observation of T1 and T2 (mcDESPOT) approach. Myelin basic protein (MBP) stain provided histological validation of the MWF. Regions of interest were placed in the maternal corpus callosum (CC), maternal fornix (FOR), fetal CC, and fetal FOR in MWF maps and MBP stains. Linear regression between MWF and MBP stain intensity (SI) of all four regions (coefficient of determination, R2 ). A paired t-test compared the MWF of maternal and mean fetal CC, MBP SI of maternal and mean fetal CC, MWF of maternal and mean fetal FOR, MBP SI of maternal and mean fetal FOR. A paired t-test with a linear mixed model compared the MWF of fetal CC and fetal FOR, and MBP SI of fetal CC and fetal FOR. A P value < 0.0083 was considered statistically significant. The mean MWF of the analyzed regions are as follows (mean ± standard deviation): 0.338 + 0.016 (maternal CC), 0.340 ± 0.017 (maternal FOR), 0.214 ± 0.016 (fetal CC), and 0.305 ± 0.025 (fetal FOR). MWF correlated with MBP SI in all regions (R2 =0.81). Significant differences were found between MWF and MBP SI of maternal and fetal CC, and MWF and MBP SI of fetal CC and fetal FOR. This study demonstrated the feasibility of MWI in assessing fetal brain myelin content. 2 Technical Efficacy: Stage 1.

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Characterization of the active response of a guinea pig carotid artery.

This work presents a characterization of the active response of the carotid artery of guinea pig fetuses through a methodology that encompasses experiments, modeling and numerical simulation. To this end, the isometric contraction test is carried out in ring samples subjected to different levels of KCl concentrations and pre-stretching. Then, a coupled mechanochemical model, aimed at describing the smooth cell behavior and its influence on the passive and active mechanical response of the vascular tissue, is calibrated from the experimental measurements. Due to the complex stress and strain fields developed in the artery, a finite element numerical simulation of the test is performed to fit the model parameters, where those related to the phosphorylation and dephosphorylation activity along with the load-bearing capacity of the myosin cross-bridges are found to be the most predominant when sensitizing the active response. The main strengths of the model are associated with the prediction of the stationary state of the active mechanical response of the tissue through a realistic description of the mechanochemical process carried out at its cellular level.

Comparative analysis of fetal pig decomposition processes in burials of variable depths and wrapping.

This research examined the effects that the variables of burial depth and presence of plastic wrapping had on the decomposition rate of fetal pig (Sus scrofa) remains in a New England environment. The decomposition of 56 fetal pigs was observed in four independent variable groups: 20 cm depth unwrapped, 20 cm wrapped, 60 cm unwrapped, and 60 cm wrapped, with exhumation at months 1, 2, 3, 6, 9, 12, and 18. The authors hypothesized that the rate of decay would be slower for wrapped remains and/or for remains at a greater burial depth. Analysis of these remains consisted of preburial and postburial mass, adipocere coverage, skeletal exposure, and decomposition quantified as Total Body Score (TBS). The difference between preburial and postburial mass was reported as a loss percentage to account for varying preburial masses. Wrapping was a significant influencer of mass loss percentage, with p=0.0298 but not for the TBS, with p=0.17565. Burial depth did not have a significant effect on either mass loss percentage or TBS, with p=0.1956 and 0.08969, respectively. This study suggests that wrapping has a greater influence on decomposition patterns than burial depth in this environment, particularly the mass loss percentage. It is suggested that there are limitations with the use of TBS in Postmortem Interval (PMI) estimation, such as variable burial conditions and body characteristics.

Functional Reconstruction of Denervated Muscle by Xenotransplantation of Neural Cells from Porcine to Rat.

Neural cell transplantation targeting peripheral nerves is a potential treatment regime for denervated muscle atrophy. This study aimed to develop a new therapeutic technique for intractable muscle atrophy by the xenotransplantation of neural stem cells derived from pig fetuses into peripheral nerves. In this study, we created a denervation model using neurotomy in nude rats and transplanted pig-fetus-derived neural stem cells into the cut nerve stump. Three months after transplantation, the survival of neural cells, the number and area of regenerated axons, and the degree of functional recovery by electrical stimulation of peripheral nerves were compared among the gestational ages (E 22, E 27, E 45) of the pigs. Transplanted neural cells were engrafted at all ages. Functional recovery by electric stimulation was observed at age E 22 and E 27. This study shows that the xenotransplantation of fetal porcine neural stem cells can restore denervated muscle function. When combined with medical engineering, this technology can help in developing a new therapy for paralysis.