Nucleostemin Expression Research Articles

Myocardial ischemia-reperfusion injury upregulates nucleostemin expression via HIF-1α and c-Jun pathways and alleviates apoptosis by promoting autophagy

Myocardial ischemia-reperfusion (I/R) injury, often arising from interventional therapy for acute myocardial infarction, leads to irreversible myocardial cell death. While previous studies indicate that nucleostemin (NS) is induced by myocardial I/R injury and mitigates myocardial cell apoptosis, the underlying mechanisms are poorly understood. Here, our study reveals that NS upregulation is critical for preventing cardiomyocyte death following myocardial I/R injury. Elevated NS protein levels were observed in myocardial I/R injury mouse and rat models, as well as Hypoxia/reoxygenation (H/R) cardiac cell lines (H9C2 cells). We identified binding sites for c-Jun and HIF-1α in the NS promoter region. Inhibition of JNK and HIF-1α led to a significant decrease in NS transcription and protein expression. Furthermore, inhibition of autophagy and NS expression promoted myocardial cell apoptosis in H/R. Notably, the cell model showed reduced LC3I transformation to LC3II, downregulated Beclin1, upregulated p62, and altered expression of autophagy-related proteins upon NS interference in H/R cells. These findings suggest that NS expression, driven by c-Jun and HIF-1α pathways, facilitates autophagy, providing protection against both myocardial I/R injury and H/R-induced cardiomyocyte apoptosis.

8805 Nucleostemin is a novel bifunctional transcriptional coregulator of theandrogenreceptorin prostate cancer cells

Abstract Disclosure: E. Cheung: None. C. Zhang: None. Androgen receptor (AR) is a master transcriptional regulator in prostate cancer, interacting with and recruiting distinct sets of coregulator proteins to mediate the expression of direct target genes. What are the coregulators of AR and how they function in AR transcriptional activity and prostate cancer biology are still unclear. Using chromatin-immunoprecipitation coupled with mass spectrometry, we identified a set of AR interacting proteins that are present in multiple prostate cancer cell lines. We provide biochemical, cell-based, and genomic evidence to show that Nucleostemin, also known as Guanine nucleotide-binding protein-like 3, is a novel AR coregulator. Specifically, we demonstrate Nucleostemin has dual coregulator activities, functioning as both a coactivator and a corepressor of AR-dependent transcription to regulate the expression of genes that are involved for prostate cancer progression and immune response. From cellular and animal studies, we found that inhibiting Nucleostemin sensitizes prostate cancer cells to Enzalutamide. Clinical analyses of Nucleostemin from prostate cancer patient cohorts revealed that it is expressed significantly higher in cancer than normal in tissues. Finally, we found Nucleostemin expression is an excellent predictor of disease-free survival. In conclusion, our work suggests that Nucleostemin is a novel AR coregulator and is a promising diagnostic and therapeutic target for prostate cancer treatment. Presentation: 6/2/2024

Relationship of Telomerase Inhibitor 1 (PinX1) and Nucleostemin (GNL3) Expression with Telomerase Reverse Transcriptase (TERT) Concentration in Myeloid and Erythroid Origin Cell Groups

Relationship of Telomerase Inhibitor 1 (PinX1) and Nucleostemin (GNL3) Expression with Telomerase Reverse Transcriptase (TERT) Concentration in Myeloid and Erythroid Origin Cell Groups

Quinacrine Induces Nucleolar Stress in Treatment-Refractory Ovarian Cancer Cell Lines.

Simple SummaryA high mortality rate in ovarian cancer imposes the need for improved therapy; most patients initially respond to systemic chemotherapy but later relapse with fatal treatment-refractory tumors. We previously evaluated repurposing the antimalarial agent quinacrine as an anticancer agent in chemoresistant ovarian cancer. Quinacrine has a long history of use in humans and we have demonstrated selectivity characteristics for reducing drug resistant tumors. In this study, we analyze different responses to quinacrine between drug resistant and sensitive cell lines to identify major pathways related to this selectivity. We confirm our results in notoriously drug resistant high-grade serous ovarian cancer cells and describe nucleostemin as a new quinacrine target related to ribosomal biogenesis and nucleolar stress. This study provides preclinical evidence that quinacrine may be effective against relapsed/refractory ovarian cancer.A considerable subset of gynecologic cancer patients experience disease recurrence or acquired resistance, which contributes to high mortality rates in ovarian cancer (OC). Our prior studies showed that quinacrine (QC), an antimalarial drug, enhanced chemotherapy sensitivity in treatment-refractory OC cells, including artificially generated chemoresistant and high-grade serous OC cells. In this study, we investigated QC-induced transcriptomic changes to uncover its cytotoxic mechanisms of action. Isogenic pairs of OC cells generated to be chemoresistant and their chemosensitive counterparts were treated with QC followed by RNA-seq analysis. Validation of selected expression results and database comparison analyses indicated the ribosomal biogenesis (RBG) pathway is inhibited by QC. RBG is commonly upregulated in cancer cells and is emerging as a drug target. We found that QC attenuates the in vitro and in vivo expression of nucleostemin (NS/GNL3), a nucleolar RBG and DNA repair protein, and the RPA194 catalytic subunit of Pol I that results in RBG inhibition and nucleolar stress. QC promotes the redistribution of fibrillarin in the form of extranuclear foci and nucleolar caps, an indicator of nucleolar stress conditions. In addition, we found that QC-induced downregulation of NS disrupted homologous recombination repair both by reducing NS protein levels and PARylation resulting in reduced RAD51 recruitment to DNA damage. Our data suggest that QC inhibits RBG and this inhibition promotes DNA damage by directly downregulating the NS–RAD51 interaction. Additionally, QC showed strong synergy with PARP inhibitors in OC cells. Overall, we found that QC downregulates the RBG pathway, induces nucleolar stress, supports the increase of DNA damage, and sensitizes cells to PARP inhibition, which supports new therapeutic stratagems for treatment-refractory OC. Our work offers support for targeting RBG in OC and determines NS to be a novel target for QC.

Targeted micelles with chemotherapeutics and gene drugs to inhibit the G1/S and G2/M mitotic cycle of prostate cancer

BackgroundChemotherapy and gene therapy are used in clinical practice for the treatment of castration-resistant prostate cancer. However, the poor efficiency of drug delivery and serious systemic side effects remain an obstacle to wider application of these drugs. Herein, we report newly designed PEO-PCL micelles that were self-assembled and modified by spermine ligand, DCL ligand and TAT peptide to carry docetaxel and anti-nucleostemin siRNA.ResultsThe particle size of the micelles was 42 nm, the zeta potential increased from − 12.8 to 15 mV after grafting with spermine, and the optimal N/P ratio was 25:1. Cellular MTT experiments suggested that introduction of the DCL ligand resulted in high toxicity toward PSMA-positive cells and that the TAT peptide enhanced the effect. The expression of nucleostemin was significantly suppressed in vitro and in vivo, and the tumour-inhibition experiment showed that the dual-drug delivery system suppressed CRPC tumour proliferation.ConclusionsThis targeted drug delivery system inhibited the G1/S and G2/M mitotic cycle via synergistic interaction of chemotherapeutics and gene drugs.

Expression of nucleostemin in odontogenic cysts and tumors

Considering the unique clinical behavior of odontogenic cysts and tumors, this study aimed to assess the expression of nucleostemin in odontogenic cysts and tumors by immunohistochemical (IHC) staining. This retrospective study evaluated 50 samples including 13 samples of unicystic ameloblastoma (UA), 10 samples of solid ameloblastoma (SA), 10 samples of odontogenic keratocyst (OKC) and 17 samples of dentigerous cyst (DC) by IHC staining. The stained slides were evaluated under a light microscope. Number of positively stained cells for nucleostemin marker was counted in five random areas per 100 cells under x400 magnification. The labeling index (LI) for nucleostemin was calculated by dividing the number of positively stained cells by the total number of counted cells in each lesion multiplied by 100. Positive staining for nucleostemin marker was observed in 100% of SA,100% of UA, 100% of OKC and 5 samples of DC (29.4%). The LI for nucleostemin marker in SA (median: 70.5), UA (median: 50) and OKC (median: 52) samples was significantly higher than that in DC (median: 0.00) (P = .001). This study showed an increased expression of nucleostemin in ameloblastoma and OKC, which suggests that stemness may be related to development of these lesions, their invasive behavior and high rate of recurrence.

Prognostic value of stem cell markers in esophageal and esophagogastric junction cancer: a meta-analysis.

Background: Esophageal cancer is an aggressive tumor, with poor prognosis and low survival rates. Although diagnosis and treatment have improved considerably, more efficient prognostic factors are urgently needed to prevent postoperative recurrence and metastasis. Cancer stem cells are key players in tumor progression and several studies have investigated the association between the expression of stemness genes and clinical outcome. However, the prognostic value of stemness markers in esophageal cancer remains controversial. We identified six factors involved in angiogenesis, anti-apoptosis and self-renewal that have been associated to poor prognosis in other types of cancer. We conducted a review of the literature and a meta-analysis to assess their potential prognostic role in this malignancy.Material and Methods: The database of PMC, PubMed, Web of Science, Embase and The Cochrane Library were searched to investigate the association between CD34, CD133, Nucleostemin, OCT-4, NANOG and CD90, and the survival of patients affected by esophageal squamous cell carcinoma or esophageal adenocarcinoma. Among the 615 eligible studies, a total of 19 articles (including 1586 patients) met the inclusion criteria for the meta-analysis, and the pooled hazard ratio and 95% confidence intervals were calculated.Results: Data showed that high expression of CD34 (HR 2.10; 95%CI 1.41-3.14; I2=56%; p=0.0003), CD133 (HR 1.91; 95%CI 1.15-3.19; I2=55%; p=0.01) and Nucleostemin (HR 2.97; 95%CI 1.11-7.98; I2=0%; p=0.03) were associated with poor prognosis in patients affected by esophageal cancer. The expression of NANOG and OCT-4 showed no significant association with survival of patients, whereas no study involving CD90 was included in this meta-analysis. Conclusion: CD34, CD133 and Nucleostemin might represent useful prognostic markers in patients affected by esophageal cancer.

Nucleostemin expression in breast cancer is a marker of more aggressive phenotype and unfavorable patients' outcome: A STROBE-compliant article.

Cancer stem cells (CSCs) are postulated to play significant role in the pathogenesis, progression as well as drug resistance of breast cancer. Nucleostemin (NS) is thought to be a key molecule for stemness, and the clinical impact of NS immunoreactivity in breast cancer can indicate its actual role and future therapeutic potentials.The current study is an observational study with an attempt to evaluate the correlation between NS expression (protein and gene expression levels) and different clinicopathological attributes of invasive breast cancer. For that reason, we investigated NS immunohistochemistry expression on commercial tissue microarray (TMA) of 102 patients and 51 archival specimens from patients admitted to Saqr Hospital, Ras Al Khaimah and diagnosed in Al Baraha Hospital, Dubai, UAE. In addition, the association between NS (GNL3) gene expression and different prognostic parameters as well as patient outcome was also evaluated using 2 large publicly available databases.Interestingly, we found NS expression to be associated with less differentiated and more advance stage. In addition, NS expression was significantly higher in larger size (P = .001) and LN-positive tumors (P = .007). Notably, NS expression was significantly correlated to P53 positive (P = .037) status. Furthermore, NS was found to be more expressed in the highly aggressive breast cancer subtypes including human epidermal growth factor receptor 2 (HER-2) and triple negative breast cancer (TNBC) subtypes. Moreover, our results also showed that high GNL3 gene expression to be associated with poor patient outcome and higher chances of tumor recurrence.Our results highlight NS expression as a marker of aggressive phenotype and poor outcome and indicate its possible use as a potential target for CSC-associated breast cancer management.

High nucleostemin expression has a favorable prognostic effect on gastric carcinomas

Background/aim: Nucleostemin is a nuclear protein that maintains stem cell features and plays a role as a cell proliferation marker. It also participates in cell cycle regulation by interfering with other intracellular proteins. Recent reports have indicated that this protein plays a role in ribosomal biogenesis and genome protection. High expression level of nucleostemin has been reported in some cancer patients. However, the importance of nucleostemin in gastric cancer needs to be addressed. The aim of this study was to investigate nucleostemin expression in gastric cancer and the effects of this expression on prognosis. Materials and methods: Nucleostemin expression was assessed in 103 patients with gastric carcinomas via immunohistochemistry. Subsequently, relationships between nucleostemin expression and clinicopathological features and prognosis were evaluated. Results: In this study, there were 33 and 70 cases involving high and low nucleostemin expression, respectively. Nucleostemin expression was negatively correlated with lymphovascular invasion, the number of metastatic lymph nodes, extracapsular extension, and T stage. Disease-free survival and overall survival were markedly longer in patients with high nucleostemin expression. Conclusion: We suggest that nucleostemin is a favorable prognostic marker for gastric cancer patients. Our results are in conflict with prior studies. The prognostic effect of nucleostemin in gastric cancer remains to be solved.

Differential expression of nucleostemin in the cytoplasm and nuclei of normal and cancerous cell lines.

Studies conducted in the past decade have reported nucleostemin (NS) as a nucleolar protein that has a role in self-renewal and cell cycle regulation in cancer/stem cells, but is absent in differentiated cells. The localization and expression patterns of NS have always been disputed, as reports indicate its varied levels among tissues and cells. This study evaluates the expression and localization pattern of NS in normal cells, cancer cell lines, and stem cells. Our findings revealed that the expression of NS was high in cancers originating from the skin and liver compared to the normal cell lines. NS knockdown effects the proliferation of normal cell lines, similar to cancerous cell lines. The localization pattern of NS was analyzed by immunofluorescence, which showed that NS was localized in the nuclei of normal cell lines but is present both in the nucleus and the cytoplasm of cancerous/stem cell lines. Interestingly, we observed that siNS cancerous cell lines had lower NS in the cytoplasm, which did not salvage the reduction in proliferation caused by siNS.We postulate that the loss of NS in the nucleus inhibits the proliferative ability of both normal and cancerous cells at similar rates, although the role of NS in the cytoplasm apart from proliferation needs to be further explored.

Influence of Nucleostemin Expression Down-Regulation on PI3K/AKT/mTOR Signal Pathway in HL-60 Cells

To explore the effect of nucleostemin(NS) RNAi on the expression of signal molecules in PI3K/AKT/mTOR pathway, a candidate of p53-independent signal pathway in the leukemia HL-60 cells. The expression of NS was interfered by transfection of P53-deficient HL-60 cells with the recombinant lentivirus expression vector NS-RNAi-GV248. The exression of NS and signal molecules of PI3K/AKT/mTOR pathway were detected by Western blot. The fluorescence microscopy showed that the recombinant lentivirus vector NS-RNAi-GV248 transfected HL-60 cells successfully with a 80% transfection rate. Western blot showed that the expression of NS protein was inhibited obviously in HL-60 cells, and the expression levels of AKT, p-AKT, p70s6k and p-p70s6k were not statistically different(t1=2.31,P>0.05;t2=3.62,P>0.05;t3=1.60,P>0.05;t4=2.72,P>0.05) in comparison with control; the expression of GβL protein was statistically down-regnlated (t=15.01,P=0.002). The changes of GβL protein correlats with NS knockdown. The PI3K/AKT/mTOR pathway may be one of nucleostemin p53-independent signal pathways.

Esophageal adenocarcinoma microenvironment: Peritumoral adipose tissue effects associated with chemoresistance.

Peritumoral microenvironment affects cancer development and chemoresistance, and visceral adipose tissue may play a critical role. We aimed to identify depot‐specific adipose characteristics associated with carcinogenesis and resistance to neoadjuvant therapy in esophageal adenocarcinoma (EAC). We analyzed: (i) the peritumoral adipose tissue of rats following the induction of esophageal carcinogenesis; (ii) the peritumoral and distal (omental) adipose tissue of patients affected by EAC; (iii) adipose‐derived stem cells (ADSC) isolated from healthy patients and treated with conditioned medium (CM), collected from tumoral and adipose tissue of patients with EAC. In peritumoral adipose tissue of rats, CD34, CD31 and vascular endothelial growth factor (VEGF) expression increased progressively during EAC development. In patients with EAC, expression of CD34, CD45, CD90 and nucleostemin (NSTM) was higher in peritumoral than in distal adipose tissue and decreased in the presence of neoadjuvant therapy. Moreover, expression of NSTM, octamer‐binding transcription factor 4 (OCT‐4) and VEGF was higher in peritumoral (but not in distal) adipose tissue of chemoresistant patients. In ADSC, treatment with peritumoral adipose tissue CM increased the adipogenic potential and the expression of CD34, CD90, NSTM and OCT‐4. These effects were similar to those induced by cancer‐derived CM, but were not observed in ADSC treated with distal adipose tissue CM and were partially reduced by a leptin antagonist. Last, ADSC treated with peritumoral CM of chemoresistant patients displayed increased expression of NSTM, OCT‐4, leptin, leptin receptor, alpha‐smooth muscle actin (α‐SMA), CD34 and VEGF. These results suggest that peritumoral adipose tissue may promote, by paracrine signaling, the expression of depot‐specific factors associated with therapeutic resistance.

Immunohistochemical expression of nucleostemin and P53 in glioma

Immunohistochemical expression of nucleostemin and P53 in glioma

Effect of Down-Regulatory Nucleostemin Expression on Autophagy Activities in p53 Null HL-60 Leukemia Cells

Based on previous microarry and bioinformatic analysis results, to investigate the effect of nucleostemin(NS) expression down-regulation on autophagy activity in p53 null HL-60 leukemia cells, so as to provide evidence for studying mechanisms of p53-independent signal pathway of NS in details. The autophagy activity of HL-60 cells after down-regulation of NS expression was detected with acidine orange staining, Western blot and transmission electron mcrioscope technique. The expression level of NS in test groups was lower than that in blank control and negative control groups after HL-60 cells were readily transinfected by lentivirus. The result of acidine orange staining showed that the number of acid vesicular organelle in test groups(22.4±0.76)% was higher than that in blank control groups(3.1±0.28)% and negative control groups(6.2±0.64)% (P<0.05). Western blot showed that the ratio of LC3II/LC3I in test groups(1.537±0.072) was higher than that in blank control and negative control groups (1.010±0.039) and (0.608±0.008). The result of transmission electron mcrioscopy also showed that the number of autophagosomes in test group(8.7±3.1) was higher than that in the blank control and negative control groups(4.2±1.2) and (2.3±0.5). Autophagy activty can be enhanced after the level of NS was down regulated. The change indicates the signaling transductions screened by bioinformatic analysis may be one of p53-independent pathway of NS, which lays a foundation for contineously studying key points of p53-independent signal pathway of NS.

Anti-carcinogenic and anti-angiogenic properties of the extracts of Acorus calamus on gastric cancer cells.

Acorus calamus (A. calamus) has been used as a medicinal plant in Asia for its effects on digestive system for the last 2000 years. To investigate the anti-cancer activity of rhizome of A. calamus, the ethanolic and methanolic extracts and essential oil of the rhizome were prepared and their effects were assessed on human gastric cancer cell line (AGS). The viability of cells which were treated with the extracts and the essential oil was assessed by MTT assay. To evaluate the anti-angiogenic property of the extracts, in vitro tube formation assay was done. Cell cycle distribution and the expression of Oct4 and Nucleostemin, after treatments, were checked by flowcytometry and quantitative RT-PCR, respectively. Furthermore, analysis of essential oil from A.calamus was done by GC-MS. Our results showed that the growth of AGS cells was inhibited by the extracts and essential oil and the extracts inhibited the angiogenesis in HUVEC cells. Our data revealed that the extracts and essential oil of A. calamus caused G1 arrest in AGS cells and downregulation of Oct4 and NS after treatment. By GC-MS analysis, we found new compounds such as epiprezizaene, valencene and isocyclocitral in essential oil of A. All together, our results showed that the extracts of A. calamus have anti-proliferative and anti-angiogenic effects on cancer cells.

Pro-metastatic intracellular signaling of the elaidic trans fatty acid.

Trans fatty acids (TFAs) are risk factors of cardiovascular disorders, and a few studies have reported the cancer-promoting effects of TFAs. In the present study, we examined the effects and signaling of elaidic acid (EA), a TFA, in colorectal cancer (CRC) cells. Oral intake of EA increased the metastasis of CT26 mouse CRC cells by inducing the expression of stemness markers nucleostemin (NS) and CD133. Mechanisms underlying EA-induced signaling were confirmed by determining the binding of EA to G-protein coupled receptor 40 (GPR40) and GPR120 by performing surface protein internalization assay. We found that c-SRC mediated EGFR transactivation was induced by the binding of EA to GPR40 and GPR120. Moreover, EGFR signaling upregulated NS and Snail expression and downregulated E-cadherin expression in wild-type APC-containing CT26 cells, and upregulated NS, Wnt5a and CD44 expression in APC-null HT29 cells. These results indicate that EA enhances the stemness and epithelial-mesenchymal transition of CRC cells. These results also indicate the prominent metastatic potential of EA-treated cancer cells and highlight the important implications of EA on public health.

Osteogenic Differentiation of Human Umbilical Cord Peri-vascular Cells using Low Intensity Pulsed Ultrasound

The objective of this experiment was to explore the possible effect of low intensity pulsed ultrasound (LIPUS) on the osteogenic differentiation of harvested passage-4 Human umbilical cord peri-vascular cells (HUCPV-Cs). HUCPV-Cs were divided into two groups: a treatment group that received LIPUS for 10 minutes for 1, 7 and 14 days and a control group that received a sham treatment utilizing osteogenic media. The results demonstrated nonsignificant differences in cell count, ALP, DNA content, and CD90. Statistically significant expression of OPN and PCNA was observed on day 14 in the LIPUS treated group. Nucleostemin expression in the LIPUS-treated group was nonsignificant on days 1 and 7. However, a selective increase in the osteogenic markers was observed in the LIPUS treated group on day 7 for ALP and OCN and on day 14 for OPN. Future experiments are required to explore the possible effects of different application times and/or techniques of LIPUS on the behaviour of HUCPV-Cs.

Nucleostemin promotes the proliferation of human glioma via Wnt/β-Catenin pathway.

Nucleostemin, nucleolar guanosine triphosphate (GTP)-binding protein 3, is a member of the MMR1/HSR1 GTP-binding protein family. The important roles of nucleostemin in self-renewal, cell cycle regulation, apoptosis, and cell proliferation of various cancer types as been shown. Nevertheless, its expression and potential functions in human glioma is still unclear. In the present study, we demonstrated that up-regulation of nucleostemin was tightly related to poor 5-year-survival ratios. In serum-starved and re-feeding models of U251 and U373MG, we observed the rising expression of nucleostemin and p-β-Catenin (p-Tyr645) were accompanied with cell proliferation markers (cyclin D1 and proliferating cell nuclear antigen (PCNA)). Employing nucleostemin-depletion models, we found down-regulated nucleostemin and p-β-Catenin. The flow cytometry analysis proved the weakened cell proliferation. Moreover, we detected the translocation of β-Catenin into the nucleus was impaired, meaning the inhibition of the Wnt/β-Catenin pathway. Taken together, we identified a positive correlation between up-regulation of nucleostemin and human glioma cell proliferation and that knocking-down nucleostemin alleviated glioma proliferation by reducing β-Catenin transportation into the nucleus. All results suggested that nucleostemin might accelerate human glioma proliferation via the Wnt/β-Catenin pathway.

Identification of Pathways Mediating Growth Differentiation Factor5-Induced Tenogenic Differentiation in Human Bone Marrow Stromal Cells.

To date, the molecular signalling mechanisms which regulate growth factors-induced MSCs tenogenic differentiation remain largely unknown. Therefore, a study to determine the global gene expression profile of tenogenic differentiation in human bone marrow stromal cells (hMSCs) using growth differentiation factor 5 (GDF5) was conducted. Microarray analyses were conducted on hMSCs cultures supplemented with 100 ng/ml of GDF5 and compared to undifferentiated hMSCs and adult tenocytes. Results of QuantiGene® Plex assay support the use and interpretation of the inferred gene expression profiles and pathways information. From the 27,216 genes assessed, 873 genes (3.21% of the overall human transcriptome) were significantly altered during the tenogenic differentiation process (corrected p<0.05). The genes identified as potentially associated with tenogenic differentiation were ARHGAP29, CCL2, integrin alpha 8 and neurofilament medium polypeptides. These genes, were mainly associated with cytoskeleton reorganization (stress fibers formation) signaling. Pathway analysis demonstrated the potential molecular pathways involved in tenogenic differentiation were: cytoskeleton reorganization related i.e. keratin filament signaling and activin A signaling; cell adhesion related i.e. chemokine and adhesion signaling; and extracellular matrix related i.e. arachidonic acid production signaling. Further investigation using atomic force microscopy and confocal laser scanning microscopy demonstrated apparent cytoskeleton reorganization in GDF5-induced hMSCs suggesting that cytoskeleton reorganization signaling is an important event involved in tenogenic differentiation. Besides, a reduced nucleostemin expression observed suggested a lower cell proliferation rate in hMSCs undergoing tenogenic differentiation. Understanding and elucidating the tenogenic differentiation signalling pathways are important for future optimization of tenogenic hMSCs for functional tendon cell-based therapy and tissue engineering.

Functionally deficient mesenchymal stem cells reside in the bone marrow niche with M2-macrophages and amyloid-β protein adjacent to loose total joint implants.

We sought to demonstrate whether there is a difference in the local mesenchymal stem cells (MSC) niche obtained from patients undergoing their first total joint replacement surgery versus those patients undergoing a revision surgery for an failing total joint implant. Bone marrow aspirates collected from patients undergoing revision total joint arthroplasty were observed to be less clonal and the expression of PDGFRα, CD51, ALCAM, endoglin, CXCL12, nestin, and nucleostemin were decreased. Revision MSC were also less able to commit to an osteoblast-lineage or an adipocyte-lineage. Further, in revision MSC, OPG, and IL6 expression were increased. Monocytes, derived from revision whole marrow aspirates, were less capable of differentiating into osteoclasts, the cells implicated in the pathologic degradation of bone. Osteoclasts were also not observed in tissue samples collected adjacent to the implants of revision patients; however, the alternatatively activated M2-macrophage phenotype was observed in parallel with pathologic accumulations of amyloid-β, τ-protien and 3-nitrotyrosine. Despite the limited numbers of patients examined, our data suggest that nucleostemin may be a useful functional marker for MSC while the observation of M2-macrophage infiltration around the implant lays the foundation for future investigation into a novel mechanism that we propose is associated with loose total joint implants.