Lentiviral transduction and subsequent loading with nanoparticles do not affect cell viability and proliferation in hair-follicle-bulge-derived stem cells in vitro

Tuning of Hydrogel Architectures by Ionotropic Gelation in Microfluidics: Beyond Batch Processing to Multimodal Diagnostics

Microfluidics is emerging as a promising tool to control physicochemical properties of nanoparticles and to accelerate clinical translation. Indeed, microfluidic-based techniques offer more advantages in nanomedicine over batch processes, allowing fine-tuning of process parameters. In particular, the use of microfluidics to produce nanoparticles has paved the way for the development of nano-scaled structures for improved detection and treatment of several diseases. Here, ionotropic gelation is implemented in a custom-designed microfluidic chip to produce different nanoarchitectures based on chitosan-hyaluronic acid polymers. The selected biomaterials provide biocompatibility, biodegradability and non-toxic properties to the formulation, making it promising for nanomedicine applications. Furthermore, results show that morphological structures can be tuned through microfluidics by controlling the flow rates. Aside from the nanostructures, the ability to encapsulate gadolinium contrast agent for magnetic resonance imaging and a dye for optical imaging is demonstrated. In conclusion, the polymer nanoparticles here designed revealed the dual capability of enhancing the relaxometric properties of gadolinium by attaining Hydrodenticity and serving as a promising nanocarrier for multimodal imaging applications.

Multimodal imaging of hair follicle bulge-derived stem cells in a mouse model of traumatic brain injury

Traumatic brain injury (TBI) is a devastating event for which current therapies are limited. Stem cell transplantation may lead to recovery of function via different mechanisms, such as cell replacement through differentiation, stimulation of angiogenesis and support to the microenvironment. Adult hair follicle bulge-derived stem cells (HFBSCs) possess neuronal differentiation capacity, are easy to harvest and are relatively immune-privileged, which makes them potential candidates for autologous stem cell-based therapy. In this study, we apply in vivo multimodal, optical and magnetic resonance imaging techniques to investigate the behavior of mouse HFBSCs in a mouse model of TBI. HFBSCs expressed Luc2 and copGFP and were examined for their differentiation capacity in vitro. Subsequently, transduced HFBSCs, preloaded with ferumoxytol, were transplanted next to the TBI lesion (cortical region) in nude mice, 2 days after injury. Brains were fixed for immunohistochemistry 58 days after transplantation. Luc2- and copGFP-expressing, ferumoxytol-loaded HFBSCs showed adequate neuronal differentiation potential in vitro. Bioluminescence of the lesioned brain revealed survival of HFBSCs and magnetic resonance imaging identified their localization in the area of transplantation. Immunohistochemistry showed that transplanted cells stained for nestin and neurofilament protein (NF-Pan). Cells also expressed laminin and fibronectin but extracellular matrix masses were not detected. After 58 days, ferumoxytol could be detected in HFBSCs in brain tissue sections. These results show that HFBSCs are able to survive after brain transplantation and suggest that cells may undergo differentiation towards a neuronal cell lineage, which supports their potential use for cell-based therapy for TBI.

Edition of Prostaglandin E2 Receptors EP2 and EP4 by CRISPR/Cas9 Technology in Equine Adipose Mesenchymal Stem Cells

In mesenchymal stem cells (MSCs), it has been reported that prostaglandin E2 (PGE2) stimulation of EP2 and EP4 receptors triggers processes such as migration, self-renewal, survival, and proliferation, and their activation is involved in homing. The aim of this work was to establish a genetically modified adipose (aMSC) model in which receptor genes EP2 and EP4 were edited separately using the CRISPR/Cas9 system. After edition, the genes were evaluated as to if the expression of MSC surface markers was affected, as well as the migration capacity in vitro of the generated cells. Adipose MSCs were obtained from Chilean breed horses and cultured in DMEM High Glucose with 10% fetal bovine serum (FBS). sgRNA were cloned into a linearized LentiCRISPRv2GFP vector and transfected into HEK293FT cells for producing viral particles that were used to transduce aMSCs. GFP-expressing cells were separated by sorting to obtain individual clones. Genomic DNA was amplified, and the site-directed mutation frequency was assessed by T7E1, followed by Sanger sequencing. We selected 11 clones of EP2 and 10 clones of EP4, and by Sanger sequencing we confirmed 1 clone knock-out to aMSC/EP2 and one heterozygous mutant clone of aMSC/EP4. Both edited cells had decreased expression of EP2 and EP4 receptors when compared to the wild type, and the edition of EP2 and EP4 did not affect the expression of MSC surface markers, showing the same pattern in filling the scratch. We can conclude that the edition of these receptors in aMSCs does not affect their surface marker phenotype and migration ability when compared to wild-type cells.

Imaging Bioluminescent Exogenous Stem Cells in the Intact Guinea Pig Cochlea

Stem-cell-based therapy may be used to replace damaged or lost neurons in the cochlear nerve of patients suffering from severe-to-profound sensorineural hearing loss. In order to achieve functional recovery in future clinical trials, knowledge about survival of grafted cells and their differentiation into functional neurons is a prerequisite. This calls for non-invasive in vivo visualization of cells and long-term monitoring of their survival and fate after cochlear transplantation. We have investigated if molecular optical imaging enables visualization of exogenous cells in the intact cochlea of guinea pig cadaver heads. Transduced (stem) cells, stably co-expressing fluorescent (copGFP) and bioluminescent (Luc2) reporter molecules, were injected into the internal auditory meatus or directly into the cochlea through the round window. After injection of the cells into the internal auditory meatus, a bright bioluminescent signal was observed in the cavum conchae of the auricle, indicating that light generated by Luc2 is passing through the tympanic membrane and the external auditory meatus. Similar results were obtained after injection of the cells through the round window membrane, either directly into the scala tympani or in Rosenthal's canal within the modiolus of the basal cochlear turn. Imaging of the auditory bulla demonstrated that the bioluminescent signal passes through the tympanic membrane and crevices in the bony wall of the bulla. After opening the auditory bulla, the bioluminescent signal was emanating from the round window. This is the first study demonstrating that bioluminescence imaging enables visualization of luciferase-expressing cells injected into the intact guinea pig cochlea. Anat Rec, 303:427-440, 2020. © 2019 The Authors. The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.

In Vivo Survival of Mesenchymal Stromal Cell-Enhanced Decellularized Nerve Grafts for Segmental Peripheral Nerve Reconstruction

PURPOSE

Adipose-derived mesenchymal stromal cells (MSCs) have emerged as promising tools for peripheral nerve reconstruction. There is a paucity of information regarding the ultimate survivorship of implanted MSCs or whether these cells remain where they are placed. The aim of the present study was to track the in vivo distribution and survival of MSCs seeded on a decellularized nerve allograft reconstruction of a peripheral nerve defect using luciferase-based bioluminescence imaging (BLI).

METHODS

To determine the in vivo survivability of MSCs, autologous Lewis rat MSCs were stably labeled with luciferase by lentiviral particles. Labeled cells were dynamically seeded onto a Sprague Dawley decellularized rat nerve allograft and used to bridge a 10-mm sciatic nerve defect. The MSC survival was determined by performing in vivo BLI to detect living cells. Twelve animals were examined at 24 hours after implantation, 3, 7, 9, 11, and 14 days, and at daily intervals thereafter if signals were still present.

RESULTS

Labeled MSCs could be detected for up to 29 days. Gradually diminishing BLI signals were observed within the first week following implantation. Implanted MSCs were not detected anywhere other than the site of surgery.

CONCLUSIONS

The MSCs seeded on decellularized nerve allografts can survive in vivo but have finite survival after implantation. There was no evidence of migration of MSCs to surrounding tissues.

CLINICAL RELEVANCE

The findings support a therapeutic approach that combines MSCs with a biological scaffold for peripheral nerve surgery. It provides understanding of the viability and distribution of implanted MSCs, which is a prerequisite before clinical translation can be considered.

Neuronal differentiation of hair-follicle-bulge-derived stem cells co-cultured with mouse cochlear modiolus explants

Stem-cell-based repair of auditory neurons may represent an attractive therapeutic option to restore sensorineural hearing loss. Hair-follicle-bulge-derived stem cells (HFBSCs) are promising candidates for this type of therapy, because they (1) have migratory properties, enabling migration after transplantation, (2) can differentiate into sensory neurons and glial cells, and (3) can easily be harvested in relatively high numbers. However, HFBSCs have never been used for this purpose. We hypothesized that HFBSCs can be used for cell-based repair of the auditory nerve and we have examined their migration and incorporation into cochlear modiolus explants and their subsequent differentiation. Modiolus explants obtained from adult wild-type mice were cultured in the presence of EF1α-copGFP-transduced HFBSCs, constitutively expressing copepod green fluorescent protein (copGFP). Also, modiolus explants without hair cells were co-cultured with DCX-copGFP-transduced HFBSCs, which demonstrate copGFP upon doublecortin expression during neuronal differentiation. Velocity of HFBSC migration towards modiolus explants was calculated, and after two weeks, co-cultures were fixed and processed for immunohistochemical staining. EF1α-copGFP HFBSC migration velocity was fast: 80.5 ± 6.1 μm/h. After arrival in the explant, the cells formed a fascicular pattern and changed their phenotype into an ATOH1-positive neuronal cell type. DCX-copGFP HFBSCs became green-fluorescent after integration into the explants, confirming neuronal differentiation of the cells. These results show that HFBSC-derived neuronal progenitors are migratory and can integrate into cochlear modiolus explants, while adapting their phenotype depending on this micro-environment. Thus, HFBSCs show potential to be employed in cell-based therapies for auditory nerve repair.