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International Journal of Bioprinting NIR-secretome release for nerve regeneration

Keywords: 3D Bioprinting; Near-Infrared Radiation; Graphene Oxide; Alginate Microbeads; Neural Regeneration

1. Introduction In this study, we propose a novel approach for
the controlled delivery of MSCs secretome for nerve
Nerve damage is a major cause of disability worldwide, with regeneration using near-infrared (NIR) radiation-
1
limited treatment options available. Neural damage refers responsive bioprinted alginate-graphene oxide (AGO)
to any injury or trauma to the cells, fibers, or pathways microbeads. 42-44 Graphene oxide (GO) is a highly
of the nervous system. It can occur in the brain, spinal biocompatible material that has shown to possess
2-4
cord, or peripheral nerves, and can result from a variety unique properties, including NIR responsiveness, which
of causes, including physical trauma, infection, toxicity, or allows for the controlled release of therapeutic agents
degenerative diseases such as Alzheimer’s or Parkinson’s. upon exposure to NIR radiation. 45,46 We hypothesized
4-9
Neural damage can have severe and often irreversible that AGO microbeads could be used to encapsulate
consequences, including loss of function, memory, and and release in a controlled manner through NIR the
cognition. 10,11 In recent years, the incidence of neural damage secretome of MSCs. To test our hypothesis, we first
has increased due to factors such as aging populations and induced controlled damage to hippocampal neurons.
the rise in traumatic brain injuries. 12,13 As a result, there is a We then encapsulated MSCs secretome in AGO
growing need for a better understanding of the mechanisms microbeads and exposed them to NIR radiation. We
underlying neural damage and the development of new then compared the effectiveness of the secretome of
therapeutic strategies to mitigate its effects. 14-16 Symptoms MSCs with the secretome from astrocytes, which is also
of nerve damage can include numbness, tingling, pain, known to promote nerve growth and proliferation. 47-52
weakness, and loss of coordination, which can significantly Our results demonstrated that the controlled release
impact an individual’s quality of life. 17-19 Despite its of MSCs secretome through non-invasive NIR from
prevalence, current treatments for neural damage are AGO microbeads promoted significant proliferation
limited, and often involve management of symptoms rather and regeneration of hippocampal neurons following
than addressing the underlying causes. 20-24 nerve injury. The use of AGO microbeads offers several
Mesenchymal stem cells (MSCs) have shown promise advantages over conventional delivery approaches,
in the treatment of neural damage due to their ability to including the ability to control the timing, location, and
differentiate into neuronal cells and modulate the immune dose of therapeutic agents, as well as the potential for
response. 25-28 However, recent studies have suggested that reduced immunogenicity and tumorigenicity. Overall,
the secretome of MSCs—the complex mixture of growth our approach provides a promising new avenue for
factors, cytokines, and extracellular vesicles they secrete— the development of MSC-based therapies for nerve
may play a key role in promoting neural regeneration. 29,30 The regeneration, with implications for the treatment of
secretome has been shown to have immunomodulatory, anti- various neuropathies and injuries.
inflammatory, and neuroprotective effects, and can promote
the survival, growth, and differentiation of neurons. 31-33 2. Materials and methods
Notably, the secretome offers distinct advantages over stem
cells themselves for stem therapies, as it can be characterized 2.1. Cell culture
and controlled more easily, allowing for precise regulation and Primary cultures of hippocampal neurons were obtained
optimization of therapeutic interventions. 34,35 This enhanced from E15-18 C57BL/6 mice embryos as described
suitability of the secretome holds the potential for more previously and in accordance with the Ethics Committee of
predictable and targeted outcomes in neural regeneration the Università Cattolica del Sacro Cuore and in compliance
therapies. However, a critical challenge associated with the with Italian Ministry of Health guidelines, with national
use of the secretome lies in its controlled administration to laws (Legislative Decree 116/1992), and European Union
53,54
the specific anatomical district where it is needed. 36,37 Unlike guidelines on animal research (No. 86/609/EEC).
the stem cells, which can be directly transplanted into the Briefly, the mouse cortex was dissected in cold CMF-
target area, the secretome requires careful delivery methods HBSS (Ca and Mg free Hank’s balanced salt solution
2+
2+
to ensure its localized and targeted action. 38,39 Strategies such containing 1 mM pyruvate, 15 mM 4-(2-hydroxyethyl)-
as encapsulation within biomaterials or the use of specialized 1-piperazineethanesulfonic acid, HEPES, and 10 mM
delivery systems are being explored to address this concern, NaHCO ). Tissues were then incubated for 10 min at 37°C
3
which is crucial to harness the full potential of the secretome in phosphate-buffered saline (PBS) containing trypsin-
in neural regeneration therapies. 40,41 ethylenediaminetetraacetic acid (0.025%/0.01% w/v;

Volume 10 Issue 1 (2024) 230 https://doi.org/10.36922/ijb.1045