Effects of systemic transplantation of adipose tissue-derived stem cells on olfactory epithelium regeneration

Tissue Engineering and Regenerative Medicine in the Field of Otorhinolaryngology

BACKGROUND

Otorhinolaryngology is a medical specialty that focuses on the clinical study and treatments of diseases within head and neck regions, specifically including the ear, nose, and throat (ENT), but excluding eyes and brain. These anatomical structures play significant roles in a person's daily life, including eating, speaking as well as facial appearance and expression, thus greatly impacting one's overall satisfaction and quality of life. Consequently, injuries to these regions can significantly impact a person's well-being, leading to extensive research in the field of tissue engineering and regenerative medicine over many years.

METHODS

This chapter provides an overview of the anatomical characteristics of otorhinolaryngologic tissues and explores the tissue engineering and regenerative medicine research in otology (ear), rhinology (nose), facial bone, larynx, and trachea.

RESULTS AND CONCLUSION

The integration of tissue engineering and regenerative medicine in otorhinolaryngology holds the promise of broadening the therapeutic choices for a wide range of conditions, ultimately improving quality of a patient's life.

Olfactory dysfunction and the role of stem cells in the regeneration of olfactory neurons

The prevalence of COVID-19 has drawn increasing attention to olfactory dysfunction among researchers. Olfactory dysfunction manifests in various clinical types, influenced by numerous pathogenic factors. Despite this diversity, the underlying pathogenesis remains largely elusive, contributing to a lack of standardized treatment approaches. However, the potential regeneration of olfactory neurons within the nasal cavity presents a promising avenue for addressing olfactory dysfunction effectively. Our review aims to delve into the current research landscape and treatment modalities concerning olfactory dysfunction, emphasizing etiology, pathogenesis, clinical interventions, and the role of stem cells in regenerating olfactory nerves. Through this comprehensive examination, we aim to provide valuable insights into understanding the onset, progression, and treatment of olfactory dysfunction diseases.

Olfactory Regeneration with Nasally Administered Murine Adipose-Derived Stem Cells in Olfactory Epithelium Damaged Mice

In this study, we aimed to determine whether nasally administered murine adipose-derived stem cells (ADSCs) could support olfactory regeneration in vivo. Olfactory epithelium damage was induced in 8-week-old C57BL/6J male mice by intraperitoneal injection of methimazole. Seven days later, OriCell adipose-derived mesenchymal stem cells obtained from green fluorescent protein (GFP) transgenic C57BL/6 mice were nasally administered to the left nostril of these mice, and their innate odor aversion behavior to butyric acid was assessed. Mice showed significant recovery of odor aversion behavior, along with improved olfactory marker protein (OMP) expression on both sides of the upper-middle part of the nasal septal epithelium assessed by immunohistochemical staining 14 d after the treatment with ADSCs compared with vehicle control animals. Nerve growth factor (NGF) was detected in the ADSC culture supernatant, NGF was increased in the nasal epithelium of mice, and GFP-positive cells were observed on the surface of the left side nasal epithelium 24 h after left side nasal administration of ADSCs. The results of this study suggest that the regeneration of olfactory epithelium can be stimulated by nasally administered ADSCs secreting neurotrophic factors, thereby promoting the recovery of odor aversion behavior in vivo.

Augmenting Peripheral Nerve Regeneration with Adipose-Derived Stem Cells

Peripheral nerve injuries (PNIs) are common and debilitating, cause significant health care costs for society, and rely predominately on autografts, which necessitate grafting a nerve section non-locally to repair the nerve injury. One possible approach to improving treatment is bolstering endogenous regenerative mechanisms or bioengineering new nervous tissue in the peripheral nervous system. In this review, we discuss critical-sized nerve gaps and nerve regeneration in rats, and summarize the roles of adipose-derived stem cells (ADSCs) in the treatment of PNIs. Several regenerative treatment modalities for PNI are described: ADSCs differentiating into Schwann cells (SCs), ADSCs secreting growth factors to promote peripheral nerve growth, ADSCs promoting myelination growth, and ADSCs treatments with scaffolds. ADSCs' roles in regenerative treatment and features are compared to mesenchymal stem cells, and the administration routes, cell dosages, and cell fates are discussed. ADSCs secrete neurotrophic factors and exosomes and can differentiate into Schwann cell-like cells (SCLCs) that share features with naturally occurring SCs, including the ability to promote nerve regeneration in the PNS. Future clinical applications are also discussed.

Achievements and Challenges in Transplantation of Mesenchymal Stem Cells in Otorhinolaryngology

Otorhinolaryngology enrolls head and neck surgery in various tissues such as ear, nose, and throat (ENT) that govern different activities such as hearing, breathing, smelling, production of vocal sounds, the balance, deglutition, facial animation, air filtration and humidification, and articulation during speech, while absence of these functions can lead to high morbidity and even mortality. Conventional therapies for head and neck damaged tissues include grafts, transplants, and artificial materials, but grafts have limited availability and cause morbidity in the donor site. To improve these limitations, regenerative medicine, as a novel and rapidly growing field, has opened a new therapeutic window in otorhinolaryngology by using cell transplantation to target the healing and replacement of injured tissues. There is a high risk of rejection and tumor formation for transplantation of embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs); mesenchymal stem cells (MSCs) lack these drawbacks. They have easy expansion and antiapoptotic properties with a wide range of healing and aesthetic functions that make them a novel candidate in otorhinolaryngology for craniofacial defects and diseases and hold immense promise for bone tissue healing; even the tissue sources and types of MSCs, the method of cell introduction and their preparation quality can influence the final outcome in the injured tissue. In this review, we demonstrated the anti-inflammatory and immunomodulatory properties of MSCs, from different sources, to be safely used for cell-based therapies in otorhinolaryngology, while their achievements and challenges have been described too.

Factors that modulate olfactory dysfunction

The olfactory system is one of a few areas in the nervous system which is capable of regeneration throughout the life. Olfactory sensory neurons reside in the nasal cavity are continuously replenished with new neurons arising from stem cells. Some factors such as aging, neurodegenerative diseases, head trauma, brain tumor extraction and infection cause olfactory dysfunction which significantly influences physical wellbeing, quality of life, mental health, nutritional status, memory processes, identifying danger and is associated with increased mortality. Therefore, finding a treatment to improve olfactory dysfunction is needed. Recent research efforts in the field have shown some very promising new approaches to treat olfactory dysfunction. This review explores the current studies that have addressed therapeutic approaches to improve olfactory neuron regeneration based on cell transplantation therapy, modulation of physiological olfactory dysfunction and drug treatments.

Engraftment and regenerative effects of bone marrow stromal cell transplantation on damaged rat olfactory mucosa

To develop a new therapeutic method to treat olfactory deficits, we investigated the engraftment and regenerative effects of transplanted bone marrow stromal cells (BMSCs) on damaged rat olfactory mucosa. To induce olfactory nerve degeneration, one side of the olfactory mucosa of Sprague-Dawley rats was damaged via Triton X-100 irrigation. Phosphate-buffered saline containing syngeneic BMSCs was injected into the olfactory mucosa for transplantation. PKH fluorescent cell dye labeling of BMSCs was used to monitor the transplanted cells. After transplantation of BMSCs, the thickness and regeneration of olfactory mucosa were analyzed using hematoxylin-eosin (H&E) staining. S100 immunohistochemical staining was used to measure nerve sheath regeneration. The increase in NGF (nerve growth factor) level in the olfactory mucosa was measured by Western blot analysis. Transplanted bone marrow stromal cells were engrafted to the lamia propria of damaged mucosa. The mean time for normalization of thickness and morphological recovery of the olfactory mucosa was 4 weeks in the therapeutic group and 9 weeks in the control group. S100 immunoreactivity was higher on the BMSC-treated side than on the control side. During regeneration, the expression of NGF increased in the olfactory mucosa of the experimental group. Based on these results, BMSC transplantation accelerated regeneration of olfactory mucosa damaged by Triton X-100, and NGF may be essential to this regenerative process.

Cellular kinetics of perivascular MSC precursors

Mesenchymal stem/stromal cells (MSCs) and MSC-like multipotent stem/progenitor cells have been widely investigated for regenerative medicine and deemed promising in clinical applications. In order to further improve MSC-based stem cell therapeutics, it is important to understand the cellular kinetics and functional roles of MSCs in the dynamic regenerative processes. However, due to the heterogeneous nature of typical MSC cultures, their native identity and anatomical localization in the body have remained unclear, making it difficult to decipher the existence of distinct cell subsets within the MSC entity. Recent studies have shown that several blood-vessel-derived precursor cell populations, purified by flow cytometry from multiple human organs, give rise to bona fide MSCs, suggesting that the vasculature serves as a systemic reservoir of MSC-like stem/progenitor cells. Using individually purified MSC-like precursor cell subsets, we and other researchers have been able to investigate the differential phenotypes and regenerative capacities of these contributing cellular constituents in the MSC pool. In this review, we will discuss the identification and characterization of perivascular MSC precursors, including pericytes and adventitial cells, and focus on their cellular kinetics: cell adhesion, migration, engraftment, homing, and intercellular cross-talk during tissue repair and regeneration.

Studies in adipose-derived stromal cells: migration and participation in repair of cranial injury after systemic injection

BACKGROUND

Adipose-derived stromal cells are a multipotent cell type with the ability to undergo osteogenic differentiation. The authors sought to examine whether systemically administered adipose-derived stromal cells would migrate to and heal surgically created defects of the mouse cranial skeleton.

METHODS

Mouse adipose-derived stromal cells were harvested from luciferase-positive transgenic mice; human adipose-derived stromal cells were harvested from human lipoaspirate and labeled with luciferase and green fluorescent protein. A 4-mm calvarial defect (critical sized) was made in the mouse parietal bone; skin incisions alone were used as a control (n = 5 per group). Adipose-derived stromal cells were injected intravenously (200,000 cells per animal) and compared with saline injection only. Methods of analyses included micro-computed tomographic scanning, in vivo imaging system detection of luciferase activity, and standard histology.

RESULTS

Migration of adipose-derived stromal cells to calvarial defect sites was confirmed by accumulation of luciferase activity and green fluorescent protein stain as early as 4 days and persisting up to 4 weeks. Little activity was observed among control groups. Intravenous administration of either mouse or human adipose-derived stromal cells resulted in histologic evidence of bone formation within the defect site, in comparison with an absence of bone among control defects. By micro-computed tomographic analysis, human but not mouse adipose-derived stromal cells stimulated significant osseous healing.

CONCLUSIONS

Intravenously administered adipose-derived stromal cells migrate to sites of calvarial injury. Thereafter, intravenous human adipose-derived stromal cells contribute to bony calvarial repair. Intravenous administration of adipose-derived stromal cells may be an effective delivery method for future efforts in skeletal regeneration.

Transplantation of neural stem cells in anosmic mice

OBJECTIVES

Treating olfactory dysfunction is a challenge for physicians. One of the therapeutic options could be transplantation of stem cells. In this study, neural stem cells were transplanted into anosmic mice.

METHODS

Neural stem cells were generated from the olfactory bulb of green fluorescent protein (GFP)-transgenic C57BL6 mice. Anosmia were induced by injection of intraperitoneal 3-methylindole. The neural stem cells were transplanted transnasally on the next day. The olfactory function was evaluated by a food-finding test once a week. The olfactory neuroepithelium was harvested for histologic examination and protein analysis at 4 weeks.

RESULTS

Twenty-five percent (6/24) of the control mice that were not transplanted with neural stem cells survived at 4 weeks while 67% (8/12) of the transplanted mice survived (P=0.029). The food finding test showed that the transplanted mice resumed finding food at 3 weeks while the control mice resumed finding food at 4 weeks. GFP-positive cells were observed in the olfactory neuroepithelium of the transplanted mice. Western blotting revealed that the olfactory marker protein expression was significantly lower in the control mice than that in the transplanted mice.

CONCLUSION

This study demonstrated that improvement of mouse survival was achieved and recovery of olfactory function was promoted by transnasal transplantation of neural stem cells in the anosmic mouse model. These results indicate that stem cells might be one of the future modalities for treating olfactory impairment.

Treatment of stress urinary incontinence with adipose tissue-derived stem cells

BACKGROUND AIMS

Effective treatment for stress urinary incontinence (SUI) is lacking. This study investigated whether transplantation of adipose tissue-derived stem cells (ADSC) can treat SUI in a rat model.

METHODS

Rats were induced to develop SUI by postpartum vaginal balloon dilation and bilateral ovariectomy. ADSC were isolated from the peri-ovary fat, examined for stem cell properties, and labeled with thymidine analog BrdU or EdU. Ten rats received urethral injection of saline as a control. Twelve rats received urethral injection of EdU-labeled ADSC and six rats received intravenous injection of BrdU-labeled ADSC through the tail vein. Four weeks later, urinary voiding function was assessed by conscious cystometry. The rats were then killed and their urethras harvested for tracking of ADSC and quantification of elastin, collagen and smooth muscle contents.

RESULTS

Cystometric analysis showed that eight out 10 rats in the control group had abnormal voiding, whereas four of 12 (33.3%) and two of six (33.3%) rats in the urethra-ADSC and tail vein-ADSC groups, respectively, had abnormal voiding. Histologic analysis showed that the ADSC-treated groups had significantly higher elastin content than the control group and, within the ADSC-treated groups, rats with normal voiding pattern also had significantly higher elastin content than rats with voiding dysfunction. ADSC-treated normal-voiding rats had significantly higher smooth muscle content than control or ADSC-treated rats with voiding dysfunction.

CONCLUSIONS

Transplantation of ADSC via urethral or intravenous injection is effective in the treatment and/or prevention of SUI in a pre-clinical setting.