Browsing by Author "Jara, Claudia"
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Item Microencapsulation of cellular aggregates composed of diferentiated insulin and glucagon-producing cells from human mesenchymal stem cells derived from adipose tissue(2020) Jara, Claudia; Oyarzun‑Ampuero, Felipe; Carrión, Flavio; González‑Echeverría, Esteban; Cappelli, ClaudioBackground: In type I diabetes mellitus (T1DM) pancreatic β cells are destroyed. Treatment entails exogenous insulin administration and strict diet control, yet optimal glycemic control is hardly attainable. Islet transplant could be an alternative in patients with poor glycemic control, but inefcient islet purifcation and autoimmune response of patients is still a challenge. For these reasons, it is necessary to explore new cellular sources and immunological isolation methods oriented to develop T1DM cell-based therapies. Aims: We postulate human adipose-derived stem cell (hASC) as an adequate source to generate pancreatic islet cells in vitro, and to produce islet-like structures. Furthermore, we propose microencapsulation of these aggregates as an immunological isolation strategy. Methods: hASC obtained from lipoaspirated fat tissue from human donors were diferentiated in vitro to insulin (Ins) and glucagon (Gcg) producing cells. Then, insulin producing cells (IPC) and glucagon producing cells (GPC) were cocultured in low adhesion conditions to form cellular aggregates, and later encapsulated in a sodium alginate polymer. Expression of pancreatic lineage markers and secretion of insulin or glucagon in vitro were analyzed. Results: The results show that multipotent hASC efciently diferentiate to IPC and GPC, and express pancreatic markers, including insulin or glucagon hormones which they secrete upon stimulation (fvefold for insulin in IPC, and fourfold for glucagon, compared to undiferentiated cells). In turn, calculation of the Feret diameter and area of cellular aggregates revealed mean diameters of ~80 µm, and 65% of the aggregates reached 4000 µm2 at 72 h of formation. IPC/GPC aggregates were then microencapsulated in sodium-alginate polymer microgels, which were found to be more stable when stabilized with Ba2+, yielding average diameters of ~300 µm. Interestingly, Ba2+-microencapsulated aggregates respond to high external glucose with insulin secretion.Publication PKR-driven ISR signaling controls synaptic translation and structural plasticity in an age-dependent manner(2025) Martínez, Nicolás; Gómez, Felipe; Tapia, Ariel; Roa, Juan; Moreso, Fernanda; Liu, Yuwei; Jara, Claudia; Tapia, Cheril; Alfaro, Ivan; Costa, Mauro; Matus, SoledadThe integrated stress response (ISR) modulates protein homeostasis in response to both intracellular and extracellular signals. The four kinases involved in the ISR all phosphorylate the same target, the alpha subunit of eukaryotic initiation factor 2 (eIF2α), to integrate various stress signals, thereby regulating cell fate. The activation of the ISR reprograms the proteome by inhibiting general protein synthesis while increasing the translation of specific mRNAs. In the brain, the ISR regulates the type of synaptic plasticity necessary for forming long-term memory. More importantly, the activation of the ISR has emerged as a causal mechanism underlying cognitive decline associated with a wide range of neurological disorders, prompting several pharmaceutical companies to target the ISR to promote brain health. However, whether the ISR acts at specific localities within neurons, including synapses, remains unclear. Here, we examined the presence, activity, and spatial arrangement of the ISR branch driven by the double-stranded RNA-dependent protein kinase (PKR) (PKR-eIF2α axis) in synapses and assessed the role of PKR in maintaining synaptic proteostasis over time. Our findings demonstrate that both PKR and eIF2α are localized at synapses, where a dynamic PKR-eIF2α axis regulates synaptic size and the abundance of synaptic proteins in an age-dependent manner. Moreover, PKR deficiency leads to an increase in protein synthesis in synapse-enriched fractions. Thus, the PKR branch of the ISR serves as a new regulator of synaptic structural plasticity.