scholarly journals An inverse-breathing encapsulation system for cell delivery

2021 ◽  
Vol 7 (20) ◽  
pp. eabd5835
Author(s):  
Long-Hai Wang ◽  
Alexander Ulrich Ernst ◽  
James Arthur Flanders ◽  
Wanjun Liu ◽  
Xi Wang ◽  
...  
Keyword(s):  
Cell Function ◽  
Waste Product ◽  
Cell Encapsulation ◽  
Permeable Membrane ◽  
Encapsulated Cells ◽  
Hypoxic Conditions ◽  
Cellular Environment ◽  
Lithium Peroxide ◽  
Potential System

Cell encapsulation represents a promising therapeutic strategy for many hormone-deficient diseases such as type 1 diabetes (T1D). However, adequate oxygenation of the encapsulated cells remains a challenge, especially in the poorly oxygenated subcutaneous site. Here, we present an encapsulation system that generates oxygen (O2) for the cells from their own waste product, carbon dioxide (CO2), in a self-regulated (i.e., “inverse breathing”) way. We leveraged a gas-solid (CO2–lithium peroxide) reaction that was completely separated from the aqueous cellular environment by a gas permeable membrane. O2 measurements and imaging validated CO2-responsive O2 release, which improved cell survival in hypoxic conditions. Simulation-guided optimization yielded a device that restored normoglycemia of immunocompetent diabetic mice for over 3 months. Furthermore, functional islets were observed in scaled-up device implants in minipigs retrieved after 2 months. This inverse breathing device provides a potential system to support long-term cell function in the clinically attractive subcutaneous site.

scholarly journals Survival and Proliferation under Severely Hypoxic Microenvironments Using Cell-Laden Oxygenating Hydrogels

2021 ◽  
Vol 12 (2) ◽  
pp. 30
Author(s):  
Shabir Hassan ◽  
Berivan Cecen ◽  
Ramon Peña-Garcia ◽  
Fernanda Roberta Marciano ◽  
Amir K. Miri ◽  
...  
Keyword(s):  
Prolonged Release ◽  
Therapeutic Approaches ◽  
Encapsulated Cells ◽  
Hypoxic Conditions ◽  
Skeletal Myoblasts ◽  
Artificial Tissue ◽  
Delivery Platform ◽  
Living Tissues

Different strategies have been employed to provide adequate nutrients for engineered living tissues. These have mainly revolved around providing oxygen to alleviate the effects of chronic hypoxia or anoxia that result in necrosis or weak neovascularization, leading to failure of artificial tissue implants and hence poor clinical outcome. While different biomaterials have been used as oxygen generators for in vitro as well as in vivo applications, certain problems have hampered their wide application. Among these are the generation and the rate at which oxygen is produced together with the production of the reaction intermediates in the form of reactive oxygen species (ROS). Both these factors can be detrimental for cell survival and can severely affect the outcome of such studies. Here we present calcium peroxide (CPO) encapsulated in polycaprolactone as oxygen releasing microparticles (OMPs). While CPO releases oxygen upon hydrolysis, PCL encapsulation ensures that hydrolysis takes place slowly, thereby sustaining prolonged release of oxygen without the stress the bulk release can endow on the encapsulated cells. We used gelatin methacryloyl (GelMA) hydrogels containing these OMPs to stimulate survival and proliferation of encapsulated skeletal myoblasts and optimized the OMP concentration for sustained oxygen delivery over more than a week. The oxygen releasing and delivery platform described in this study opens up opportunities for cell-based therapeutic approaches to treat diseases resulting from ischemic conditions and enhance survival of implants under severe hypoxic conditions for successful clinical translation.

scholarly journals Hypoxia Alters the Expression of Dipeptidyl Peptidase 4 and Induces Developmental Remodeling of Human Preadipocytes

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Helena H. Chowdhury ◽  
Jelena Velebit ◽  
Nataša Radić ◽  
Vito Frančič ◽  
Marko Kreft ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Transmembrane Protein ◽  
Human Adipose Tissue ◽  
Dipeptidyl Peptidase ◽  
Dipeptidyl Peptidase 4 ◽  
Hypoxic Conditions ◽  
Human Preadipocytes ◽  
Developmental Remodeling

Dipeptidyl peptidase 4 (DPP4), a transmembrane protein, has been identified in human adipose tissue and is considered to be associated with obesity-related type 2 diabetes. Since adipose tissue is relatively hypoxic in obese participants, we investigated the expression of DPP4 in human preadipocytes (hPA) and adipocytes in hypoxia, during differentiation and upon insulin stimulation. The results show that DPP4 is abundantly expressed in hPA but very sparsely in adipocytes. During differentiationin vitro, the expression of DPP4 in hPA is reduced on the addition of differentiation medium, indicating that this protein can be hPA marker. Long term hypoxia altered the expression of DPP4 in hPA. Inin vitrohypoxic conditions the protease activity of shed DPP4 is reduced; however, in the presence of insulin, the increase in DPP4 expression is potentiated by hypoxia.

scholarly journals Deteriorating beta‐cell function in type 2 diabetes: a long‐term model

QJM ◽  
2003 ◽  
Vol 96 (4) ◽  
pp. 281-288 ◽  
Author(s):  
A. Bagust ◽  
S. Beale
Keyword(s):  
Type 2 Diabetes ◽  
Beta Cell ◽  
Beta Cell Function ◽  
Cell Function ◽  
Term Model

scholarly journals Grafting of Encapsulated Dopamine-Secreting Cells in Parkinson's Disease: Long-Term Primate Study

2000 ◽  
Vol 9 (5) ◽  
pp. 705-709 ◽  
Author(s):  
Isao Date ◽  
Tetsuro Shingo ◽  
Hideyuki Yoshida ◽  
Kenjiro Fujiwara ◽  
Kazuki Kobayashi ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Pc12 Cells ◽  
Tumor Formation ◽  
Functional Improvement ◽  
Functional Changes ◽  
Polymer Encapsulation ◽  
Encapsulated Cells ◽  
Fluid Analysis

The transplantation of encapsulated dopamine-secreting cells into the striatum represents one potential means of treating Parkinson's disease. The present study investigated the ability of encapsulated PC12 cells, which are derived from rat pheochromocytoma, to supply L-dopa and dopamine into the primate brain in the long term and to effect functional improvement in the animals. Following polymer encapsulation, PC12 cells were transplanted into the striatum of hemiparkinsonian monkeys. The secretion of L-dopa and dopamine from the encapsulated cells, the morphology of these cells, the histology of the host striatum surrounding the capsule, and functional changes in the host animals were examined 1, 6, and 12 months after transplantation. Analysis of retrieved capsules revealed that the PC12 cells survived and continued to release L-dopa and dopamine even 12 months after transplantation. The histological response of the host brain surrounding the capsules was minimal and there were no signs of immunological rejection or tumor formation. The physical condition of the host animals was good for 12 months, and hematologic and cerebrospinal fluid analysis revealed that no animals suffered from infection or immunological reaction. These PC12 cell-grafted monkeys showed improvements in hand movements after transplantation, effects that lasted for at least 12 months. These results further support the potential use of this approach for the treatment of Parkinson's disease.

scholarly journals Adventitial Alterations Are the Main Features in Pulmonary Artery Remodeling due to Long-Term Chronic Intermittent Hypobaric Hypoxia in Rats

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Julio Brito ◽  
Patricia Siques ◽  
Silvia M. Arribas ◽  
Angel L. López de Pablo ◽  
M. Carmen González ◽  
...  
Keyword(s):  
Pulmonary Artery ◽  
Right Ventricle ◽  
Inflammatory Cells ◽  
Cell Number ◽  
Hypoxic Conditions ◽  
Artery Remodeling ◽  
Medial Hypertrophy ◽  
The Right ◽  
Pulmonary Artery Remodeling

Long-term chronic intermittent exposure to altitude hypoxia is a labor phenomenon requiring further research. Using a rat model, we examined whether this type of exposure differed from chronic exposure in terms of pulmonary artery remodeling and other features. Rats were subjected to chronic hypoxia (CH,n=9) and long-term intermittent hypoxia (CIH2x2; 2 days of hypoxia/2 days of normoxia,n=10) in a chamber (428 Torr, 4,600 m of altitude) for 46 days and compared to rats under normoxia (NX,n=10). Body weight, hematocrit, and right ventricle ratio were measured. Pulmonary artery remodeling was assessed using confocal microscopy of tissues stained with a nuclear dye (DAPI) and CD11b antibody. Both hypoxic conditions exhibited increased hematocrit and hypertrophy of the right ventricle, tunica adventitia, and tunica media, with no changes in lumen size. The medial hypertrophy area (larger in CH) depicted a significant increase in smooth muscle cell number. Additionally, CIH2x2 increased the adventitial hypertrophy area, with an increased cellularity and a larger prevalence of clustered inflammatory cells. In conclusion, CIH2x2 elicits milder effects on pulmonary artery medial layer muscularization and subsequent right ventricular hypertrophy than CH. However, CIH2x2 induces greater and characteristic alterations of the adventitial layer.

scholarly journals Leydig Cell Function in Long-term Testosterone-immunized Rats

1983 ◽  
Vol 4 (1) ◽  
pp. 95-103 ◽  
Author(s):  
RICHARD M. SHARPE ◽  
HAMISH M. FRASER
Keyword(s):  
Leydig Cell ◽  
Cell Function ◽  
Leydig Cell Function

Loss of FancC Function Results in Decreased Hematopoietic Stem Cell Repopulating Ability

Blood ◽  
1999 ◽  
Vol 94 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Laura S. Haneline ◽  
Troy A. Gobbett ◽  
Rema Ramani ◽  
Madeleine Carreau ◽  
Manuel Buchwald ◽  
...  
Keyword(s):  
Stem Cell ◽  
Hematopoietic Stem Cell ◽  
Cell Function ◽  
Genetic Disorder ◽  
Test Cell ◽  
Hematopoietic Stem ◽  
Murine Homologue ◽  
Complex Genetic Disorder

Fanconi anemia (FA) is a complex genetic disorder characterized by progressive bone marrow (BM) aplasia, chromosomal instability, and acquisition of malignancies, particularly myeloid leukemia. We used a murine model containing a disruption of the murine homologue ofFANCC (FancC) to evaluate short- and long-term multilineage repopulating ability of FancC −/− cells in vivo. Competitive repopulation assays were conducted where “test”FancC −/− or FancC +/+ BM cells (expressing CD45.2) were cotransplanted with congenic competitor cells (expressing CD45.1) into irradiated mice. In two independent experiments, we determined that FancC −/− BM cells have a profound decrease in short-term, as well as long-term, multilineage repopulating ability. To determine quantitatively the relative production of progeny cells by each test cell population, we calculated test cell contribution to chimerism as compared with 1 × 105 competitor cells. We determined that FancC −/− cells have a 7-fold to 12-fold decrease in repopulating ability compared with FancC +/+cells. These data indicate that loss of FancC function results in reduced in vivo repopulating ability of pluripotential hematopoietic stem cells, which may play a role in the development of the BM failure in FA patients. This model system provides a powerful tool for evaluation of experimental therapeutics on hematopoietic stem cell function.

scholarly journals The structure and flexibility analysis of the Arabidopsis Synaptotagmin 1 reveal the basis of its regulation at membrane contact sites

2021 ◽  
Author(s):  
Juan Luis Benavente ◽  
Dritan Siliqi ◽  
Lourdes Infantes ◽  
Laura Lagartera ◽  
Alberto Mills ◽  
...  
Keyword(s):  
Cell Function ◽  
Lipid Extraction ◽  
Membrane Lipid ◽  
Lipid Binding ◽  
Lipid Transfer ◽  
C2 Domains ◽  
Membrane Contact Sites ◽  
Contact Sites ◽  
Cellular Environment ◽  
Synaptotagmin 1

Cell function requires the maintenance of membrane lipid homeostasis as changes in cellular environment unbalance this equilibrium. The non-vesicular lipid transfer at endoplasmic reticulum (ER) and plasma membrane (PM) contact sites (CS) is central to restore it. Extended synaptotagmins (E-Syts) are ER proteins that play a central role in this process as they act as molecular tethers with PM and as lipid transfer proteins between these organelles. E-Syts are constitutively anchored to the ER through an N-terminal hydrophobic segment and bind to the PM via C-terminal C2 domains. In plants, synaptotagmins (SYTs) are orthologous of E-Syts and regulate the ER-PM communication by the activity of their two C2 domains in response to abiotic stresses. We have combined macromolecular crystallography, small-angle X-ray scattering, structural bioinformatics and biochemical data to analyze the regulation of plant synaptotagmin 1 (SYT1). Our data show that the binding of SYT1 to the PM is regulated by the interaction of the first C2 domain through a Ca2+-dependent lipid binding site and by a site for phosphorylated forms of phosphatidylinositol in such a way that two different molecular signals are integrated in response to stress. In addition, our data show that SYT1 is highly flexible by virtue of up to three hinge points, including one that connects the two C2 domains. This feature provides conformational freedom to SYT1 to define a large and complementary interaction surface with the PM. This structural plasticity, in turn, may facilitate lipid extraction, protein loading and subsequent transfer between PM and ER.

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