Isolation, expansion, differentiation, and histological processing of human nasal epithelial cells

Bioengineering Human Upper Respiratory Mucosa: A Systematic Review of the State of the Art of Cell Culture Techniques

BACKGROUND

The upper respiratory mucosa plays a crucial role in both the physical integrity and immunological function of the respiratory tract. However, in certain situations such as infections, trauma, or surgery, it might sustain damage. Tissue engineering, a field of regenerative medicine, has found applications in various medical fields including but not limited to plastic surgery, ophthalmology, and urology. However, its application to the respiratory system remains somewhat difficult due to the complex morphology and histology of the upper respiratory tract. To date, a culture protocol for producing a handleable, well-differentiated nasal mucosa has yet to be developed. The objective of this review is to describe the current state of research pertaining to cell culture techniques used for producing autologous healthy human upper respiratory cells and mucosal tissues, as well as describe its clinical applications.

METHODS

A search of the relevant literature was carried out with no time restriction across Embase, Cochrane, PubMed, and Medline Ovid databases. Keywords related to "respiratory mucosa" and "culture techniques of the human airway" were the focus of the search strategy for this review. The risk of bias in retained studies was assessed using the Joanna Briggs Institute's (JBI) critical appraisal tools for qualitative research. A narrative synthesis of our results was then conducted.

RESULTS

A total of 33 studies were included in this review, and thirteen of these focused solely on developing a cell culture protocol without further use. The rest of the studies used their own developed protocol for various applications such as cystic fibrosis, pharmacological, and viral research. One study was able to develop a promising model for nasal mucosa that could be employed as a replacement in nasotracheal reconstructive surgery.

CONCLUSIONS

This systematic review extensively explored the current state of research regarding cell culture techniques for producing tissue-engineered nasal mucosa. Bioengineering the nasal mucosa holds great potential for clinical use. However, further research on mechanical properties is essential, as the comparison of engineered tissues is currently focused on morphology rather than comprehensive mechanical assessments.

Utilizing primary human airway mucociliary tissue cultures to model ramifications of chronic E-cigarette usage

Electronic cigarettes are battery powered devices that use a vape-liquid to produce a vapor that is inhaled. A consequence of the rise in e-cigarette usage was the 2019 emergence of a vaping-induced respiratory disease denoted as 'e-cigarette or vaping use-associated lung injury' (EVALI). One of the suspected causes of EVALI is Vitamin E Acetate (VEA), which was found to be a diluent in certain illicit vape-pens, whereas nicotine is commonly diluted in equal parts propylene glycol and vegetable glycerin (PG:VG). The prevalent use of e-cigarettes and the emergence of a novel illness has made understanding how e-cigarette vapors affect our respiratory tissues a public health concern. We have designed and produced a simple device that can operate e-cigarettes and deliver the vapor to a chamber containing a standard cell culture multi-well plate. Here we utilize our device to model the response of human airway mucociliary tissue after chronic exposure to vapors produced from either PG:VG or VEA. We note several differences between how PG:VG and VEA vapors interact with and alter airway tissue cultures and suggest potential mechanisms for how VEA-vapors can exacerbate EVALI symptoms. Our device combined with primary human airway tissue cultures make an economical and compact model system that allows for animal-free investigations into the acute and chronic consequences of e-cigarette vapors on primary respiratory cells.

Surfactant protein D prevents mucin overproduction in airway goblet cells via SIRPα

Mucin overproduction is a common feature of chronic airway diseases such as asthma and chronic obstructive pulmonary disease (COPD), and exacerbates their underlying respiratory condition. Surfactant protein D (SP-D) protects against airway diseases through modulation of immune reactions, but whether it also exerts direct effects on airway epithelial cells has remained unclear. Therefore, we sought to investigate the inhibitory role of SP-D on mucin production in airway epithelial cells. We prepared air-liquid interface (ALI) cultures of human primary bronchial epithelial cells (HBECs), which recapitulated a well-differentiated human airway epithelium. Benzo(a)pyrene (BaP), a key toxicant in cigarette smoke, induced mucin 5AC (MUC5AC) production in ALI-cultured HBECs, airway secretory cell lines, and airway epithelia of mice. Then, the protective effects of SP-D against the BaP-induced mucin overproduction were examined. BaP increased MUC5AC production in ALI cultures of HBECs, and this effect was attenuated by SP-D. SP-D also suppressed the BaP-induced phosphorylation of extracellular signal-regulated kinase (ERK) and MUC5AC expression in NCI-H292 goblet-like cells, but not in NCI-H441 club-like cells. Signal regulatory protein α (SIRPα) was found to be expressed in HBECs and NCI-H292 cells but absent in NCI-H441 cells. In NCI-H292 cells, SP-D activated SH2 domain-containing tyrosine phosphatase-1 (SHP-1), downstream of SIRPα, and knockdown of SIRPα abolished the suppressive effects of SP-D on BaP-induced ERK phosphorylation and MUC5AC production. Consistent with these in vitro findings, intratracheal instillation of SP-D prevented the BaP-induced phosphorylation of ERK and Muc5ac expression in airway epithelial cells in a mouse model. SP-D acts directly on airway epithelial cells to inhibit mucin secretion through ligation of SIRPα and SHP-1-mediated dephosphorylation of ERK. Targeting of SIRPα is therefore a potential new therapeutic approach to suppression of mucin hypersecretion in chronic airway diseases such as COPD and asthma.

Culture expansion of primary human nasal epithelial cells (NEC) isolated with a nasal scraping spoon

OBJECTIVE

To obtain high-purity nasal epithelial cells (NEC) while avoiding the irritation experienced by patients during nasal biopsies.

METHODS

This prospective, observational study enrolled patients undergoing surgical treatment for nasal septum deviation. After general anaesthesia, a novel nasal scraping spoon was used to collect epithelial cells from the mid-part of the inferior turbinate. The cells were evenly plated on six-well plates coated with rat tail collagen. The morphology and growth of the cells were observed at different time-points using an inverted phase-contrast microscope. Immunofluorescent staining of cytokeratin 18 was used to identify NEC. Ki67 staining was used to check cell viability.

RESULTS

This study collected samples from 19 patients during a short procedure. No postoperative complications were observed. Cell samples ranging from 8.31 × 105 to 2.04 × 106 cells/sample were obtained. The culture model was suitable for primary NEC culture as demonstrated by the faster proliferation (5-7 days). There was no fungal or bacterial contamination. Immunofluorescent staining confirmed the presence and proliferative activity of NEC in the cultures.

CONCLUSION

A novel nasal scraping spoon provided an easy sampling method, avoided nasal injuries and psychological barriers to sampling and sufficient viable NEC to establish primary cultures.

Simple, low-cost, and well-performing method, the outgrowth technique, for the isolation of cells from nasal polyps

BACKGROUND

Epithelial cells are an important part of the pathomechanism in chronic rhinosinusitis with nasal polyps. It is therefore essential to establish a robust method for the isolation and culture of epithelial cells from nasal polyps to enable further research. In this study, the feasibility of the outgrowth technique for the isolation of the epithelial cells from the nasal polyps was evaluated.

RESULTS

Using the outgrowth technique, epithelial cells could be isolated from all tissue samples. Isolated epithelial cells showed a proliferation rate of approximately 7- to 23-fold every 6 days up to the 3rd passage. Over 97% of isolated cells were shown to be cytokeratin- and p63-positive, and over 86% of them were Ki-67-positive in flow cytometry. Interleukin-33 and periostin were detectable in the supernatant.

CONCLUSIONS

We introduce a simple, low-cost, and well-performing method for isolating epithelial cells from nasal polyps with the outgrowth technique.

Long-Term Cryopreservation of Nasal Polyp Tissue in a Biobank for the Isolation and Culture of Primary Epithelial Cells

Epithelial cells may play an important role in the pathologic process of chronic rhinosinusitis with nasal polyps. Therefore, providing epithelial cells from a biobank could greatly contribute to further research. In the present work, the isolation of epithelial cells from long-term cryopreserved tissue is demonstrated. Polyp tissues were cryopreserved in a commercially available freezing medium with dimethyl sulfoxide and stored in liquid nitrogen. The outgrowth and proliferation of epithelial cells from cryopreserved tissue were evaluated and compared to that of fresh tissue. Flow cytometric analysis with anti-cytokeratin, anti-p63, and anti-Ki-67 was performed to identify epithelial cells and determine differentiation and proliferation. A functionality test was performed by determining type 2-relevant proteins, representatively thymic stromal lymphopoietin (TSLP) and periostin, using ELISA. Primary epithelial cells could be isolated from cryopreserved tissues. Cells from cryopreserved tissues showed comparable outgrowth and proliferation to that of fresh tissue. Isolated epithelial cells showed high cytokeratin, p63, and Ki-67 expression and secreted TSLP and periostin. In the present study, a method for long-term cryopreservation of polyp tissue was established, thereby enabling the isolation and cell culture of primary cell culture at a later time. Epithelial cell availability should be greatly improved by including this method in a biobank.

The dynamic nature of the Coronavirus receptor, angiotensin-converting enzyme 2 (ACE2) in differentiating airway epithelia

Once inhaled, SARS-CoV-2 particles enter respiratory ciliated cells by interacting with angiotensin converting enzyme 2 (ACE2). Understanding the nature of ACE2 within airway tissue has become a recent focus particularly in light of the COVID-19 pandemic. Airway mucociliary tissue was generated in-vitro using primary human nasal epithelial cells and the air-liquid interface (ALI) model of differentiation. Using ALI tissue, three distinct transcript variants of ACE2 were identified. One transcript encodes the documented full-length ACE2 protein. The other two transcripts are unique truncated isoforms, that until recently had only been predicted to exist via sequence analysis software. Quantitative PCR revealed that all three transcript variants are expressed throughout differentiation of airway mucociliary epithelia. Immunofluorescence analysis of individual ACE2 protein isoforms exogenously expressed in cell-lines revealed similar abilities to localize in the plasma membrane and interact with the SARS CoV 2 spike receptor binding domain. Immunohistochemistry on differentiated ALI tissue using antibodies to either the N-term or C-term of ACE2 revealed both overlapping and distinct signals in cells, most notably only the ACE2 C-term antibody displayed plasma-membrane localization. We also demonstrate that ACE2 protein shedding is different in ALI Tissue compared to ACE2-transfected cell lines, and that ACE2 is released from both the apical and basal surfaces of ALI tissue. Together, our data highlights various facets of ACE2 transcripts and protein in airway mucociliary tissue that may represent variables which impact an individual's susceptibility to SARS-CoV-2 infection, or the severity of Covid-19.