Biology subjects

Alt, C.

Publications and source records attributed to Alt, C..

4 recordsLinked to original sources

bioRxiv2024

Modulation of microglia activation after human donor retinal ganglion cell transplantation

Stem cell-derived retinal ganglion cell transplantation therapy offers a promising avenue for restoring vision in patients with significant retinal ganglion cell loss. The major challenge in this therapeutic approach is ensuring the survival of transplanted human donor retinal ganglion cells within the host retina. Here, we demonstrated the pivotal role of host retinal microglia and macrophages in the rejection, acceptance and survival of human donor cells. To identify the potential targets for treatment in microglia-retinal ganglion cell interaction, we assembled a single-cell atlas for mouse retina during development, aging, maturation and across neurodegenerative conditions. To our knowledge, this is the largest integrated atlas containing 1,053,629 cells including 36,080 myeloid cells. The downstream analysis highlighted phagocytosis among other known pathways involved in microglia activation, neuroinflammation and host retinal ganglion cell damage. We hypothesized that the same mechanisms are responsible for donor retinal ganglion cell removal. We showed that it is possible to improve the survival of human donor stem cell-derived retinal ganglion cells through modulation of the host retinal microglia. Pretreatment of human donor retinal ganglion cells with annexin V and/or soluble Fas ligand before transplantation led to a 2.5-fold increase in donor cell survival, including the outgrowth of axons targeting optic nerve head. Detailed analyses of the host mouse retina post-transplantation revealed morphological changes microglia and macrophages typical for activation in neuroinflammation. These findings indicate that soluble Fas ligand and annexin V treatment can be used to improve the success rate of transplantation of neurons within the retina and central nervous system.

cell biology↗

bioRxiv2024

New, biomechanically sound tendon tissue after injection of uncultured, autologous, adipose derived regenerative cells in partial Achilles tendon defects in rabbits

BackgroundCurrent management options for partial tendon tears may not offer future potential to heal tissue and improve clinical results. This study tested the hypothesis that treatment of a partial rabbit common calcaneus tendon (CCT) defect with uncultured, autologous, adipose derived regenerative cells (UA-ADRCs) enables regenerative healing without scar formation, as recently observed in a biopsy of a human supraspinatus tendon. MethodsA full-thickness hole (diameter, 3 mm) was punched into the midsubstance of the right gastrocnemius tendon (GT; which is a part of the CCT) of adult, female New Zealand white rabbits. Immediately thereafter the rabbits were treated by application of an averaged 28.3x106 UA-ADRCs in 0.5 ml lactated Ringers solution (RLS) into the GT defect and surrounding tendon tissue, or underwent sham treatment. Rabbits were sacrificed either four weeks (W4) or twelve weeks (W12) post-treatment, and the CCTs were investigated using histology, immunohistochemistry and non-destructive biomechanical testing. ResultsNewly formed connective tissue was consistent with the formation of new tendon tissue after treatment with UA-ADRCs, and with the formation of scar tissue after sham treatment, at both W4 and W12 post-treatment. Biomechanical testing demonstrated a significantly higher mean percent relaxation after treatment with UA-ADRCs than after sham treatment (p < 0.05), and significant, negative correlations between the peak stress as well as the equilibrium stress and the cross-sectional area of the CCT (p < 0.05) after treatment with UA-ADRCs but not after sham treatment. ConclusionsManagement of partial tendon tears with UA-ADRCs has the potential to be truly "structure-modifying".

bioengineering↗

bioRxiv2023

MACROPHAGES COORDINATE IMMUNE RESPONSE TO LASER-INDUCED INJURY VIA EXTRACELLULAR TRAPS

Macrophages/monocytes, the primary contributors to chronic inflammation in degenerated retinas, orchestrate intricate immune responses. They remain enigmatic in their local coordination and activation mechanisms. Innovations in experimental systems enable real-time exploration of immune cell interactions and temporal dimensions in response. In preclinical mouse models, we use in vivo microscopy to unravel how macrophages/monocytes govern microglia and PL responses spatio-temporally. Our findings underscore the pivotal role of innate immune cells, especially macrophages/monocytes, in regulating retinal repair. The absence of neutrophil and macrophage infiltration aids parenchymal integrity restoration, while their depletion, particularly macrophages/monocytes, impedes vascular recovery. Innate immune cells, when activated, release chromatin and granular proteins, forming extracellular traps (ETs), critical for tissue repair by modulating neutrophil and T-cell responses. Our investigations demonstrate that pharmacological inhibition of ETosis with Cl-amidine enhances retinal and vascular repair, surpassing the effects of blocking innate immune cell recruitment. Simultaneously, Cl-amidine treatment reshapes the inflammatory response, causing neutrophils, helper, and cytotoxic T-cells to cluster primarily in the superficial capillary plexus, affecting retinal microvasculature perfusion. Our data offer novel insights into innate immunitys role in responding to retinal damage, potentially informing more effective immunotherapeutic strategies for neurodegenerative diseases.

neuroscience↗

bioRxiv2018

Isolation of adipose tissue derived regenerative cells from human subcutaneous tissue with or without the use of an enzymatic reagent

BackgroundFreshly isolated, uncultured autologous adipose derived regenerative cells (ADRCs) have emerged as a promising tool for regenerative cell therapy. The Transpose RT system (InGeneron, Inc., Houston, TX, USA) is a system for isolating ADRCs from adipose tissue, commercially available in Europe as a CE-marked medical device and under clinical evaluation in the United States. This system makes use of the proprietary, enzymatic Matrase Reagent for isolating cells. The present study addressed the question whether the use of Matrase Reagent influences cell yield, cell viability, live cell yield, biological characteristics, physiological functions or structural properties of the ADRCs in final cell suspension.\n\nMethodsIdentical samples of subcutaneous adipose tissue from 12 subjects undergoing elective lipoplasty were processed either with or without the use of Matrase Reagent. Then, characteristics of the ADRCs in the respective final cell suspensions were evaluated.\n\nResultsCompared to non-enzymatic isolation, enzymatic isolation resulted in approximately twelve times higher mean cell yield (i.e., numbers of viable cells/ml lipoaspirate) and approximately 16 times more colony forming units. Despite these differences, cells isolated from lipoaspirate both with and without the use of Matrase Reagent were independently able to differentiate into cells of all three germ layers.\n\nDiscussionThe data of this study indicate that biological characteristics, physiological functions or structural properties relevant for the intended use were not altered or induced using Matrase Reagent. A comprehensive literature review demonstrated that isolation of ADRCs from lipoaspirate using the Transpose RT system and the Matrase Reagent results in the highest viable cell yield among all published data regarding isolation of ADRCs from lipoaspirate.

bioengineering↗