Novel human iPSC models of neuroinflammation in neurodegenerative disease and regenerative medicine

Age reprogramming: Innovations and ethical considerations for prolonged longevity (Review)

Age reprogramming and cellular rejuvenation therapies are revolutionizing the approach to aging and age-related diseases. These ground-breaking interventions target fundamental biological processes, including genomic instability, telomere attrition, and mitochondrial dysfunction, to restore cellular function and delay the onset of degenerative conditions. Emerging strategies such as epigenetic reprogramming, gene editing, stem cell therapy, and senolytic drugs show immense promise in extending health spans and potentially reversing aspects of aging. Despite marked progress in preclinical studies and early-stage clinical trials, translating these therapies into practical healthcare solutions presents significant challenges. Key issues include ensuring safety, optimizing delivery mechanisms, overcoming regulatory barriers, and addressing high costs. Moreover, ethical and economic considerations, such as equitable access and societal impacts, must be carefully addressed to prevent widening health disparities. The present review examines the current state of cellular rejuvenation research, highlighting both scientific advancements and the complex challenges associated with these therapies. With interdisciplinary collaboration, robust ethical frameworks, and scalable technological innovations, these therapies have the potential to transform healthcare. By shifting the focus from disease management to proactive health preservation, they offer a future where aging becomes a manageable and equitable process.

Revisiting the Pathogenesis of X-Linked Adrenoleukodystrophy

BACKGROUND

X-ALD is a white matter (WM) disease caused by mutations in the ABCD1 gene encoding the transporter of very-long-chain fatty acids (VLCFAs) into peroxisomes. Strikingly, the same ABCD1 mutation causes either devastating brain inflammatory demyelination during childhood or, more often, progressive spinal cord axonopathy starting in middle-aged adults. The accumulation of undegraded VLCFA in glial cell membranes and myelin has long been thought to be the central mechanism of X-ALD.

METHODS

This review discusses studies in mouse and drosophila models that have modified our views of X-ALD pathogenesis.

RESULTS

In the Abcd1 knockout (KO) mouse that mimics the spinal cord disease, the late manifestations of axonopathy are rapidly reversed by ABCD1 gene transfer into spinal cord oligodendrocytes (OLs). In a peroxin-5 KO mouse model, the selective impairment of peroxisomal biogenesis in OLs achieves an almost perfect phenocopy of cerebral ALD. A drosophila knockout model revealed that VLCFA accumulation in glial myelinating cells causes the production of a toxic lipid able to poison axons and activate inflammatory cells. Other mouse models showed the critical role of OLs in providing energy substrates to axons. In addition, studies on microglial changing substates have improved our understanding of neuroinflammation.

CONCLUSIONS

Animal models supporting a primary role of OLs and axonal pathology and a secondary role of microglia allow us to revisit of X-ALD mechanisms. Beyond ABCD1 mutations, pathogenesis depends on unidentified contributors, such as genetic background, cell-specific epigenomics, potential environmental triggers, and stochasticity of crosstalk between multiple cell types among billions of glial cells and neurons.

Targeting Active Microglia Alleviates Distal Edge of Proton Radiation-induced Neural Damage

Purpose

Proton therapy (PT) has distinct advantages in its ability to precisely target tumors while avoiding adjacent normal tissues. However, the distal edge effects of PT constrain its application. This study investigated the brain tissue response in the distal edge regions of protons and compared it with the effect of photons.

Methods and Materials

The occurrence of damage from photons and at the distal edge of protons was investigated in a murine model. Bragg peak treatment plans for murine models were optimized. Hematoxylin and eosin and immunofluorescence staining were performed along the distal margin. In addition, the approximate distance from the Bragg peak to the neuronal damage sites was calculated. Furthermore, a small-molecule inhibitor was studied for its ability to inhibit microglia activation.

Results

The distal edge brain injury murine model was successfully established. Reactive gliosis and granulovacuolar neuronal degeneration were observed in the right hemisphere of the brain in the proton irradiation group. Neuronal injuries were observed at multiple locations (the frontal lobe, thalamus, and cerebral cortex) along the distal border, but no injured neurons were detected along vertical photon irradiation exposed areas. Meanwhile, severe neural damage was seen with horizontal photon irradiation. At the distal edge of the Bragg peak (0.4633 ± 0.01856 cm), microglia with abnormal morphology accumulated. IBA1 and CD68 staining revealed activated microglia at the corresponding neuronal damage sites, indicating their involvement in irradiation-induced damage. Activated microglia were not observed with vertical photon irradiation, whereas many activated microglia were observed with horizontal photon irradiation. Moreover, asparagine endopeptidase inhibitors administered via intraperitoneal injection significantly reduced active microglia in the thalamus and cerebral cortex and alleviated brain damage.

Conclusions

This study demonstrated that proton radiation induces neuronal damage and accumulation of activated microglia at the distal edge. Targeting activated microglia may play a protective role in distal edge injury from radiation.

The Concept of Neuroglia - the State of the Art Circa 1900

Glial cells were first defined by Rudolf Virchow in 1856. About 40 years later, glial research had developed into a field distinct from the mainstream study of neurons as the central elements governing brain function. By that time, substantial knowledge about the properties of glial cells had accumulated, exemplified by five important publications by four distinguished investigators: Gustav Retzius, Michael von Lenhossek, Carl Weigert, and Hans Held. These treatises broadly summarized what was known about glial cells, comparing findings from leeches to humans. Practically speaking, these articles represent the foundation of our current knowledge. All five contributions were published in German, which at the time was one of the dominant languages for scientific exchange. This article summarizes and comments on their findings and thus provides insight into what was known about glial cells at that time. More importantly, in the Supporting Information, we provide English translations and original scans of these five publications, making them accessible to an international readership.

Discovery of Limonoids from Xylocarpus granatum as Potential Leads against Neuroinflammation

Discovery of new natural products with both anti-inflammatory effects on activated microglia and protective activity on dopaminergic neurons is a new strategy to find new drug leads against neuroinflammation in Parkinson's disease. In this work, nine new limonoids, named thaigranatumins A-I (1-9), and two new protolimonoids, named thaigranatumins J (10) and K (11), were obtained from seeds of the Thai mangrove, Xylocarpus granatum. The structures of these compounds were established by analysis of spectroscopic data, single-crystal X-ray diffraction (Cu Kα), and comparison of experimental and calculated ECD spectra. Thaigranatumin A (1), containing a C-16/C-30 δ-lactone ring-D and a tetra-substituted C8-O-C17-bridged tetrahydrofuran ring-F, is the first limonoid featuring a unique 6/6/6/6/6/5/5-fused heptacyclic framework. Thaigranatumin G (7) exhibited both inhibitory effects on the protein expression of iNOS, COX2, and IL-1β in lipopolysaccharide-stimulated mouse microglia BV2 cells and neuroprotective activity against rotenone-induced injury in mouse midbrain dopaminergic neuron MN9D cells in a dose-dependent manner. Preliminary bioassays indicated that thaigranatumin G might be a valuable lead against neuroinflammation, thus warranting further studies.