Isolation and characterization of epithelial and myogenic cells by "fishing" for the morphologically distinct cell types in rat primary periodontal ligament cultures

Type I collagen facilitates safe and reliable expansion of human dental pulp stem cells in xenogeneic serum-free culture

BACKGROUND

Human dental pulp stem cells (DPSCs) are a readily accessible and promising cell source for regenerative medicine. We recently reported that a xenogeneic serum-free culture medium (XFM) is preferable to fetal bovine serum-containing culture medium for ex vivo expansion of DPSCs; however, we observed that, upon reaching overconfluence, XFM cells developed a multilayered structure and frequently underwent apoptotic death, resulting in reduced cell yield. Therefore, we focused on optimization of the XFM culture system to avoid the undesirable death of DPSCs.

METHODS

We selected type I collagen (COL) as the optimal coating substrate for the cultureware and compared DPSCs cultured on COL in XFM (COL-XFM cells) to the conventional XFM cultures (XFM cells).

RESULTS

Our results demonstrated that COL coating facilitated significantly higher rates of cell isolation and growth; upon reaching overconfluence, cell survival and sustained proliferative potential resulted in two-fold yield compared to the XFM cells. Surprisingly, after subculturing the overconfluent COL-XFM cultures, the cells retained stem cell behavior including stable cell growth, multidifferentiation potential, stem cell phenotype, and chromosomal stability, which was achieved through HIF-1α-dependent production and uniform distribution of collagen type I and its interactions with integrins α2β1 and α11β1 at overconfluency. In contrast, cells undergoing apoptotic death within overconfluent XFM cultures had disorganized mitochondria with membrane depolarization.

CONCLUSION

The use of COL as a coating substrate promises safe and reliable handling of DPSCs in XFM culture, allowing translational stem cell medicine to achieve stable isolation, expansion, and banking of donor-derived stem cells.

Poly(butylene terephthalate) Fiber Assembly with Controllable Pore Size and Gradient Wettability: Potential in Simplifying Cell Culture Procedure

This study reports the scalable fabrication of a poly(butylene terephthalate) fiber assembly featured with controllable pore size and gradient wettability. Pore size is controlled via adjusting the throughput of melt blown process, while gradient wettability is achieved through single-sided plasma exposure and subsequent chitosan coating. When used in cell culture, the fiber assembly takes much less time in reaching a high cell collecting/releasing rate up to ≥99.5%, which is similar to that of the conventional centrifugal method. Other advantages of the fiber assembly, such as improved cell viability, reduced risk of contamination, and excellent reusability are also proved, leading us to believe its great potential in making the current cell culture procedure simpler and faster.

Establishment of xenogeneic serum-free culture methods for handling human dental pulp stem cells using clinically oriented in-vitro and in-vivo conditions

Background

Currently, ex-vivo handling of stem cells, including transport after harvest and therapeutic preparation, is generally done in culture media containing fetal bovine serum (FBS), which promotes cell attachment, proliferation, and differentiation. However, because of safety concerns associated with the use of FBS, including potential transmission of zoonotic agents and transplant rejection because of the incorporation of foreign proteins into the stem cells, there is a need for xenogeneic serum-free culture media for clinical handling of stem cells.

Methods

Dental pulp stem cells were derived from wisdom teeth donated by eight healthy volunteers and cultured in xenogeneic serum-free culture medium (XFM) or xenogeneic serum-containing culture medium (SCM). Cells were subjected to morphological, proliferation, karyotype, differentiation, marker expression, cryopreservation, and cytotoxic susceptibility analyses in vitro, as well as transplantation in vivo.

Results

In primary culture, XFM cells showed lower adhesion and slightly different morphology, although the single-cell size was similar to that of SCM cells. XFM cells exhibited typical mesenchymal stem cell (MSC) characteristics in vitro and in vivo, including marker gene/protein expression, trilineage differentiation potential, and hard, osteo-dentin tissue formation. Additionally, XFM cells maintained a normal karyotype in vitro and nontumorigenic potential in vivo; however, XFM cells were more susceptible to H₂O₂ and ultraviolet cytotoxic stimuli. XFM cells formed a multilayered structure showing excessive cell death/division in contrast to the monolayered structure of SCM cells when reaching overconfluence. Proliferation was disrupted in overconfluent XFM cells, and these cells could not be subcultured. Dimethyl sulfoxide-free cryopreserved XFM cells yielded similar results in all of the experiments.

Conclusions

This study is the first reporting successful isolation and expansion of an MSC population from donor-derived tissue (dental pulp) under xenogeneic serum-free culture conditions, as well as the application of cryopreservation, using a research strategy based on clinically oriented in-vitro and in-vivo experiments.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-017-0761-5) contains supplementary material, which is available to authorized users.

Heterogeneous Human Periodontal Ligament-Committed Progenitor and Stem Cell Populations Exhibit a Unique Cementogenic Property Under In Vitro and In Vivo Conditions

An undesirable complication that arises during dental treatments is external apical-root resorption, which causes root-cementum and root-dentin loss. To induce de novo cementogenesis, stem cell therapy is required. Cementum-forming cells (cementoblasts) are known to be differentiated from periodontal-lineage mesenchymal stem cells (MSCs), which are derived from the dental follicle (DF) in developing tissues and the periodontal ligament (PDL) in adult tissues, but the periodontal-lineage MSC type that is optimal for inducing de novo cementogenesis remains unidentified, as does the method to isolate these cells from harvested tissues. Thus, we investigated the cementogenic potential of DF- and PDL-derived MSCs that were isolated by using two widely used cell-isolation methods: enzymatic digestion and outgrowth (OG) methods. DF- and PDL-derived cells isolated by using both methods proliferated actively, and all four isolated cell types showed MSC gene/protein expression phenotype and ability to differentiate into adipogenic and chondrogenic lineages. Furthermore, cementogenic-potential analysis revealed that all cell types produced alizarin red S-positive mineralized materials in in vitro cultures. However, PDL-OG cells presented unique cementogenic features, such as nodular formation of mineralized deposits displaying a cellular intrinsic fiber cementum-like structure, as well as a higher expression of cementoblast-specific genes than in the other cell types. Moreover, in in vivo transplantation experiments, PDL-OG cells formed cellular cementum-like hard tissue containing embedded osteocalcin-positive cells, whereas the other cells formed acellular cementum-like materials. Given that the root-cementum defect is likely regenerated through cellular cementum deposition, PDL-OG cell-based therapies might potentially facilitate the de novo cellular cementogenesis required for regenerating the root defect.

Regenerative medicine for Parkinson's disease using differentiated nerve cells derived from human buccal fat pad stem cells

The purpose of this study was to evaluate the utility of human adipose stem cells derived from the buccal fat pad (hBFP-ASCs) for nerve regeneration. Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive death of dopaminergic neurons. PD is a candidate disease for cell replacement therapy because it has no fundamental therapeutic methods. We examined the properties of neural-related cells induced from hBFP-ASCs as a cell source for PD treatment. hBFP-ASCs were cultured in neurogenic differentiation medium for about 2 weeks. After the morphology of hBFP-ASCs changed to neural-like cells, the medium was replaced with neural maintenance medium. Cells differentiated from hBFP-ASCs showed neuron-like structures and expressed neuron markers (β3-tubulin, neurofilament 200, and microtubule-associated protein 2), an astrocyte marker (glial fibrillary acidic protein), or dopaminergic neuron-related marker (tyrosine hydroxylase). Induced neural cells were transplanted into a 6-hydroxydopamine (6-OHDA)-lesioned rat hemi-parkinsonian model. At 4 weeks after transplantation, 6-OHDA-lesioned rats were subjected to apomorphine-induced rotation analysis. The transplanted cells survived in the brain of rats as dopaminergic neural cells. No tumor formation was found after cell transplantation. We demonstrated differentiation of hBFP-ASCs into neural cells, and that transplantation of these neural cells improved the symptoms of model rats. Our results suggest that neurons differentiated from hBFP-ASCs would be applicable to cell replacement therapy of PD.

Practical methods for handling human periodontal ligament stem cells in serum-free and serum-containing culture conditions under hypoxia: implications for regenerative medicine

Stem cell-based therapies depend on the reliable expansion of patient-derived mesenchymal stem cells (MSCs) in vitro. The supplementation of cell culture media with serum is associated with several risks; accordingly, serum-free media are commercially available for cell culture. Furthermore, hypoxia is known to accelerate the expansion of MSCs. The present study aimed to characterize the properties of periodontal ligament-derived MSCs (PDLSCs) cultivated in serum-free and serum-containing media, under hypoxic and normoxic conditions. Cell growth, gene and protein expression, cytodifferentiation potential, genomic stability, cytotoxic response, and in vivo hard tissue generation of PDLSCs were examined. Our findings indicated that cultivation in serum-free medium does not affect the MSC phenotype or chromosomal stability of PDLSCs. PDLSCs expanded in serum-free medium exhibited more active growth than in fetal bovine serum-containing medium. We found that hypoxia does not alter the cell growth of PDLSCs under serum-free conditions, but inhibits their osteogenic and adipogenic cytodifferentiation while enabling maintenance of their multidifferentiation potential regardless of the presence of serum. PDLSCs expanded in serum-free medium were found to retain common MSC characteristics, including the capacity for hard tissue formation in vivo. However, PDLSCs cultured in serum-free culture conditions were more susceptible to damage following exposure to extrinsic cytotoxic stimuli than those cultured in medium supplemented with serum, suggesting that serum-free culture conditions do not exert protective effects against cytotoxicity on PDLSC cultures. The present work provides a comparative evaluation of cell culture in serum-free and serum-containing media, under hypoxic and normoxic conditions, for applications in regenerative medicine.

Isolation and characterization of embryonic ameloblast lineage cells derived from tooth buds of fetal miniature swine

Dental enamel formation, known as "amelogenesis," is initiated by cytodifferentiation of the ectodermally derived dental epithelium. Enamel cannot regenerate itself because once it is completely formed, ameloblasts are lost as the tooth erupts. Rodent teeth have been useful for studying the mechanisms of amelogenesis because ameloblast cell lines can be derived from the ever-growing incisors. However, higher mammals such as humans have no growing teeth, and cell lines derived from larger animals that are more similar to humans are required for higher fidelity studies. Here, we isolated embryonic enamel epithelium-derived epithelial cells from fetal swine. The explant culture of the developing deciduous molars that had been removed from the dental papilla-derived mesenchymal tissue and cells inside the tooth buds provided the epithelial cell population for the primary culture. To isolate the cell population, we performed a unique cell isolation technique called cell fishing. The isolated cells showed clear embryonic-stage ameloblast characteristics with appropriate gene/protein expressions of enamel matrix and proteinases, abundant glycogen pools, and secretory granular materials. They could be continuously subcultured several times and are presently being maintained. This cell population will facilitate the establishment of a stable cell line and allow us to characterize the definitive phenotype and functional behavior of porcine ameloblasts, which, in turn, promises to yield useful and practical findings that are more relevant than those provided by rodent studies. Finally, analysis of in vitro enamel formation will be important for engineering "bio-enamel" as a new dental therapy to restore enamel defects.

Establishment and characterization of human lingual squamous cell carcinoma cell lines designated Nialym derived from metastatic foci of lymph node, and Nialymx derived from transplanted tumor of Nialym cells

The squamous cell carcinoma cell lines Nialym was successfully established from metastatic foci of lymph nodes from a 48-year-old male Japanese patient with squamous cell carcinoma of the tongue. In addition, the Nialymx cell line was established from a transplanted tumor of Nialym cells in SCID mice. Nialym cells were angular, with neoplastic and pleomorphic features. Two types of Nialym cell were observed by electron microscopy; light cells and dark cells. The dark cells had a number of waved tonofilaments in the cytoplasm, while light cells showed poorly developed organelles. The population doubling times for Nialym and Nialymx cells were approximately, 46 and 42 h at the 10th passage. Nialym cells secreted 4.8 ng/ml VEGF and 5.9 ng/ml HGF, Nialymx cells also secreted 6.7 ng/ml VEGF and 4.3 ng/ml HGF at the 10th passage for 3 days of culture. Histopathological aspects of Nialym and Nialymx cell lines were similar. We believe that these cell lines are valuable tools for elucidating the mechanisms of cancer metastasis and developing immunotherapy and chemotherapy regimens.

Up-regulation of fatty acid oxidation in the ligament as a contributing factor of ankylosing spondylitis: A comparative proteomic study

OBJECTIVES

The present study first utilized a standardized shotgun proteomic analysis method to determine differences in protein expression of fibroblasts in the ligament between AS patients and healthy controls.

METHODS

Proteins extracted from primarily cultured FLLs from 35 AS patients and 10 normal subjects were analyzed by automated 2D-Nano-LC-ESI-MS/MS. Differentially expressed proteins were screened by 2-sample t-test and fold change. Bioinformatics analysis of differentially expressed proteins was based on the IPA. Fatty acid β-oxidation-related proteins and INSR pathway-related proteins in the ligament were confirmed by real-time PCR and Western blot.

RESULTS

A total of 556 differential proteins were screened in AS. Of them, 322 proteins were up-regulated and the remaining 234 proteins were down-regulated. GO and pathway analyses showed that six fatty acid β-oxidation-related proteins (HADHB, ECHS1, ACSL4, ACADM, ACSL1 and HADH) were up-regulated in FLL cells, which was consistent with the results obtained from real-time PCR, Western blot and MS, while INSR pathway-related proteins (INSR, IRS1, PI3K and PKC) was low in the ligament of AS as compared with that in healthy controls.

CONCLUSION

The lower body fat level in AS maybe due to up-regulation of fatty acid β-oxidation-related enzymes regulated by INSR/PI3K/PKC pathway.

BIOLOGICAL SIGNIFICANCE

Ankylosing spondylitis (AS), a common spondyloarthropathy, is an inflammatory rheumatic disease with a predilection for the axial skeleton. Clinical hallmarks of AS include sacroiliitis, uveitis, enthesitis and persistent spinal inflammation. The pathogenic mechanism of disease causation and perpetuation remains poorly understood. In this study, we primarily cultured fibroblast cells from ligament biopsies, knowing that fibroblast cells are dominant cells in the diseased ligament. One of the characteristic pathologic changes in AS is inflammation of the attachment points, including the muscle, ligament and bone or joint capsule. Inflammation of the tendon attachment point is usually non-bacterial and can lead to pain and swelling of the tendon ligament. To obtain more information, we used Shotgun proteomic analysis based on multidimensional liquid chromatography tandem mass spectrometry (LC-MS/MS). we firstly mixed the lysates of FLL cells derived from the ligaments of 35 AS patients and 10 normal subjects, identified proteins by automated 2D-Nano-LC-ESI-MS/MS method, GO and pathway analyses showed that six fatty acid β-oxidation-related proteins (HADHB, ECHS1, ACSL4, ACADM, ACSL1 and HADH) were up-regulated in the ligament, which was consistent with the results obtained from real-time PCR, Western blot and MS, while INSR pathway-related proteins (INSR, IRS1, PI3K and PKC) was low in the ligament of AS as compared with that in healthy controls. We also find that AS subjects had significantly lower body mass index (BMI) and BMI Z-scores compared with that in healthy controls. The results remind us that up-regulation of fatty acid β-oxidation-related proteins lower the body fat content, which is a new discovery contributing to the progression of AS. This is the first report on fatty acid oxidation in AS. It was found that the body fat level was low in AS due to high fatty acid oxidation, suggesting that insulin signaling may play an important role in the metabolic switch from predominant to fatty acid metabolism that characterizes the ligament of AS. One mechanism for this transition is increased expression of genes that regulate the rate of fatty acid oxidation. This effect may be mediated by PI3K, a downstream mediator of many receptor tyrosine kinases, including the INSR. This is a newly discovered factor contributing to the progression of AS.