FoxA2 regulates the type II collagen-induced nucleus pulposus-like differentiation of adipose-derived stem cells by activation of the Shh signaling pathway

Signaling Mechanisms of Stem Cell Therapy for Intervertebral Disc Degeneration

Low back pain is the leading cause of disability worldwide. Intervertebral disc degeneration (IDD) is the primary clinical risk factor for low back pain and the pathological cause of disc herniation, spinal stenosis, and spinal deformity. A possible approach to improve the clinical practice of IDD-related diseases is to incorporate biomarkers in diagnosis, therapeutic intervention, and prognosis prediction. IDD pathology is still unclear. Regarding molecular mechanisms, cellular signaling pathways constitute a complex network of signaling pathways that coordinate cell survival, proliferation, differentiation, and metabolism. Recently, stem cells have shown great potential in clinical applications for IDD. In this review, the roles of multiple signaling pathways and related stem cell treatment in IDD are summarized and described. This review seeks to investigate the mechanisms and potential therapeutic effects of stem cells in IDD and identify new therapeutic treatments for IDD-related disorders.

Removal of collagen three-dimensional scaffold bubbles utilizing a vacuum suction technique

The process of generating type I/II collagen scaffolds is fraught with bubble formation, which can interfere with the three-dimensional structure of the scaffold. Herein, we applied low-temperature vacuum freeze-drying to remove mixed air bubbles under negative pressure. Type I and II rubber sponges were acid-solubilized via acid lysis and enzymolysis. Thereafter, vacuum negative pressure was applied to remove bubbles, and the cover glass press method was applied to shape the type I/II original scaffold. Vacuum negative pressure was applied for a second time to remove any residual bubbles. Subsequent application of carbamide/N-hydroxysuccinimide cross-linked the scaffold. The traditional method was used as the control group. The structure and number of residual bubbles and pore sizes of the two scaffolds were compared. Based on the relationship between the pressure and the number of residual bubbles, a curve was created, and the time of ice formation was calculated. The bubble content of the experimental group was significantly lower than that of the control group (P < 0.05). The pore diameter of the type I/II collagen scaffold was higher in the experimental group than in the control group. The time of icing effect of type I and II collagen solution was 136.54 ± 5.26 and 144.40 ± 6.45 s, respectively. The experimental scaffold had a more regular structure with actively proliferating chondrocytes that possessed adherent pseudopodia. The findings indicated that the vacuum negative pressure method did not affect the physical or chemical properties of collagen, and these scaffolds exhibited good biocompatibility with chondrocytes.

Metabolic Glycoengineering: A Promising Strategy to Remodel Microenvironments for Regenerative Therapy

Cell-based regenerative therapy utilizes the differentiation potential of stem cells to rejuvenate tissues. But the dynamic fate of stem cells is calling for precise control to optimize their therapeutic efficiency. Stem cell fate is regulated by specific conditions called "microenvironments." Among the various factors in the microenvironment, the cell-surface glycan acts as a mediator of cell-matrix and cell-cell interactions and manipulates the behavior of cells. Herein, metabolic glycoengineering (MGE) is an easy but powerful technology for remodeling the structure of glycan. By presenting unnatural glycans on the surface, MGE provides us an opportunity to reshape the microenvironment and evoke desired cellular responses. In this review, we firstly focused on the determining role of glycans on cellular activity; then, we introduced how MGE influences glycosylation and subsequently affects cell fate; at last, we outlined the application of MGE in regenerative therapy, especially in the musculoskeletal system, and the future direction of MGE is discussed.

Collagen Niches Affect Direct Transcriptional Conversion toward Human Nucleus Pulposus Cells via Actomyosin Contractility

Cellular niches play fundamental roles in regulating cellular behaviors. However, the effect of niches on direct converted cells remains unexplored. In the present study, the specific combination of transcription factors is first identified to directly acquire induced nucleus pulposus-like cells (iNPLCs). Next, tunable physical properties of collagen niches are fabricated based on various crosslinking degrees. Collagen niches significantly affect actomyosin cytoskeleton and then influence the maturation of iNPLCs. Using gain- and loss of function approaches, the appropriate physical states of collagen niches are found to significantly enhance the maturation of iNPLCs through actomyosin contractility. Moreover, in a rat model of degenerative disc diseases, iNPLCs with collagen niches are transplanted into the lesion to achieve significant improvements. As a result, overexpression of transcription factors in human dermal fibroblasts are efficiently converted into iNPLCs and the optimal collagen niches affect cellular cytoskeleton and then facilitate iNPLCs maturation toward human nucleus pulposus cells. These findings encourage more in-depth studies toward the interactions of niches and direct conversion, which would contribute to the development of direct conversion.

Suppression of Sost/Sclerostin and Dickkopf-1 Augment Intervertebral Disc Structure in Mice

Intervertebral disc (IVD) degeneration is a leading cause of low back pain, characterized by accelerated extracellular matrix breakdown and IVD height loss, but there is no approved pharmacological therapeutic. Deletion of Wnt ligand competitor Lrp5 induces IVD degeneration, suggesting that Wnt signaling is essential for IVD homeostasis. Therefore, the IVD may respond to neutralization of Wnt ligand competitors sost(gene)/sclerostin(protein) and/or dickkopf-1 (dkk1). Anti-sclerostin antibody (scl-Ab) is an FDA-approved bone therapeutic that activates Wnt signaling. We aimed to (i) determine if pharmacological neutralization of sclerostin, dkk1, or their combination would stimulate Wnt signaling and augment IVD structure and (ii) determine the prolonged adaptation of the IVD to global, persistent deletion of sost. Nine-week-old C57Bl/6J female mice (n = 6-7/group) were subcutaneously injected 2×/week for 5.5 weeks with scl-Ab (25 mg/kg), dkk1-Ab (25 mg/kg), 3:1 scl-Ab/dkk1-Ab (18.75:6.25 mg/kg), or vehicle (veh). Separately, IVD of sost KO and wild-type (WT) mice (n = 8/group) were harvested at 16 weeks of age. First, compared with vehicle, injection of scl-Ab, dkk1-Ab, and 3:1 scl-Ab/dkk1-Ab similarly increased lumbar IVD height and β-catenin gene expression. Despite these similarities, only injection of scl-Ab alone strengthened IVD mechanical properties and decreased heat shock protein gene expressions. Genetically and compared with WT, sost KO enlarged IVD height, increased proteoglycan staining, and imbibed IVD hydration. Notably, persistent deletion of sost was compensated by upregulation of dkk1, which consequently reduced the cell nuclear fraction for Wnt signaling co-transcription factor β-catenin in the IVD. Lastly, RNA-sequencing pathway analysis confirmed the compensatory suppression of Wnt signaling and revealed a reduction of cellular stress-related pathways. Together, suppression of sost/sclerostin or dkk1 each augmented IVD structure by stimulating Wnt signaling, but scl-Ab outperformed dkk1-Ab in strengthening the IVD. Ultimately, postmenopausal women prescribed scl-Ab injections to prevent vertebral fracture may also benefit from a restoration of IVD height and health. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Overexpression of FOXA2 attenuates cigarette smoke-induced cellular senescence and lung inflammation through inhibition of the p38 and Erk1/2 MAPK pathways

Chronic obstructive pulmonary disease (COPD) is characterized by irreversible and progressive airflow limitation and encompasses varying degrees of chronic obstructive bronchitis and emphysema. Our previous study showed that Forkhead box protein A2 (FOXA2) is involved in cigarette smoke (CS)-induced squamous metaplasia. However, the contribution of FOXA2 activity to CS-induced cellular senescence and lung inflammation remains largely unknown. Here, we report that FOXA2 was underexpressed in CS-exposed mouse lungs, and decreased expression of FOXA2 was related to cell senescence and inflammation. Subsequent investigation suggested that FOXA2 is an anti-senescence factor in lung that is involved in inflammatory responses. Furthermore, FOXA2 overexpression delayed CSE-induced senescence and inflammation, which correlated with regulation of the p38 and Erk1/2 MAPK signaling pathways by CSE-induced FOXA2 downregulation. Collectivelly, these findings reveal a protective role for FOXA2 as a regulator of cell senescence and inflammation during COPD.

Injectable kartogenin and apocynin loaded micelle enhances the alleviation of intervertebral disc degeneration by adipose-derived stem cell

Cell transplantation has been proved the promising therapeutic effects on intervertebral disc degeneration (IVDD). However, the increased levels of reactive oxygen species (ROS) in the degenerated region will impede the efficiency of human adipose-derived stem cells (human ADSCs) transplantation therapy. It inhibits human ADSCs proliferation, and increases human ADSCs apoptosis. Herein, we firstly devised a novel amphiphilic copolymer PEG-PAPO, which could self-assemble into a nanosized micelle and load lipophilic kartogenin (KGN), as a single complex (PAKM). It was an injectable esterase-responsive micelle, and showed controlled release ability of KGN and apocynin (APO). Oxidative stimulation promoted the esterase activity in human ADSCs, which accelerate degradation of esterase-responsive micelle. Compared its monomer, the PAKM micelle possessed better bioactivities, which were attributed to their synergistic effect. It enhanced the viability, autophagic activation (P62, LC3 II), ECM-related transcription factor (SOX9), and ECM (Collagen II, Aggrecan) maintenance in human ADSCs. Furthermore, it is demonstrated that the injection of PAKM with human ADSCs yielded higher disc height and water content in rats. Therefore, PAKM micelles perform promoting cell survival and differentiation effects, and may be a potential therapeutic agent for IVDD.

Directed Differentiation of Notochord-like and Nucleus Pulposus-like Cells Using Human Pluripotent Stem Cells

Intervertebral disc degeneration might be amenable to stem cell therapy, but the required cells are scarce. Here, we report the development of a protocol for directed in vitro differentiation of human pluripotent stem cells (hPSCs) into notochord-like and nucleus pulposus (NP)-like cells of the disc. The first step combines enhancement of ACTIVIN/NODAL and WNT and inhibition of BMP pathways. By day 5 of differentiation, hPSC-derived cells express notochordal cell characteristic genes. After activating the TGF-β pathway for an additional 15 days, qPCR, immunostaining, and transcriptome data show that a wide array of NP markers are expressed. Transcriptomically, the in vitro-derived cells become more like in vivo adolescent human NP cells, driven by a set of influential genes enriched with motifs bound by BRACHYURY and FOXA2, consistent with an NP cell-like identity. Transplantation of these NP-like cells attenuates fibrotic changes in a rat disc injury model of disc degeneration.

Osmolarity controls the differentiation of adipose-derived stem cells into nucleus pulposus cells via histone demethylase KDM4B

Adipose-derived stem cells (ADSCs) are an ideal source of cells for intervertebral disc (IVD) regeneration, but the effect of an increased osmotic microenvironment on ADSC differentiation remains unclear. Here, we aimed to elucidate whether hyperosmolarity facilitates ADSC nucleus pulposus (NP)-like differentiation and whether histone demethylase KDM4B is involved in this process. ADSCs were cultured under standard and increased osmolarity conditions for 1-3 weeks, followed by analysis for proliferation and viability. Differentiation was then quantified by gene and protein analysis. Finally, KDM4B knockdown ADSCs were generated using lentiviral vectors. The results showed that increasing the osmolarity of the differentiation medium to 400 mOsm significantly increased NP-like gene expression and the synthesis of extracellular matrix (ECM) components during ADSC differentiation; however, further increasing the osmolarity to 500 mOsm suppressed the NP-like differentiation of ADSCs. KDM4B, as well as the IVD formation regulators forkhead box (Fox)a1/2 and sonic hedgehog (Shh), were found to be significantly upregulated at 400 mOsm. KDM4B knockdown reduced Foxa1/2, Shh, and NP-associated markers' expression, as well as the synthesis of ECM components. The reduction in NP-like differentiation caused by KDM4B knockdown was partially rescued by Purmorphamine, a specific agonist of Shh. Moreover, we found that KDM4B can directly bind to the promoter region of Foxa1/2 and decrease the content of H3K9me3/2. In conclusion, our results indicate that a potential optimal osmolarity window might exist for successful ADSC differentiation. KDM4B plays an essential role in regulating the osmolarity-induced NP-like differentiation of ADSCs by interacting with Foxa1/2-Shh signaling.

A Review of Gene Therapy Delivery Systems for Intervertebral Disc Degeneration

Background: :

Intervertebral Disc (IVD) degeneration is a major public health concern, and gene therapy seems a promising approach to delay or even reverse IVD degeneration. However, the delivery system used to transfer exogenous genes into intervertebral disc cells remains a challenge.

Methods::

The MEDLINE, Web of Science, and Scopus databases were searched for English-language articles related to gene therapy for IVD degeneration articles from 1999 to May 2019. The keywords included “gene therapy” AND “intervertebral disc”. The history of the development of different delivery systems was analysed, and the latest developments in viral and non-viral vectors for IVD degeneration treatment were reviewed.

Results: :

Gene therapy delivery systems for IVD degeneration are divided into two broad categories: viral and non-viral vectors. The most commonly used viral vectors are adenovirus, adeno-associated virus (AAV), and lentivirus. Enthusiasm for the use of adenovirus vectors has gradually declined and has been replaced by a preference for lentivirus and AAV vectors. New technologies, such as RNAi and CRISPR, have further enhanced the advantage of viral vectors. Liposomes are the classic non-viral vector, and their successors, polyplex micelles and exosomes, have more potential for use in gene therapy for IVD degeneration.

Conclusion::

Lentivirus and AAV are the conventional viral vectors used in gene therapy for IVD degeneration, and the new technologies RNAi and CRISPR have further enhanced their advantages. Nonviral vectors, such as polyplex micelles and exosomes, are promising gene therapy vectors for IVD degeneration.

Biomaterials-Induced Stem Cells Specific Differentiation Into Intervertebral Disc Lineage Cells

Stem cell therapy, which promotes stem cells differentiation toward specialized cell types, increases the resident population and production of extracellular matrix, and can be used to achieve intervertebral disc (IVD) repair, has drawn great attention for the development of IVD-regenerating materials. Many materials that have been reported in IVD repair have the ability to promote stem cells differentiation. However, due to the limitations of mechanical properties, immunogenicity and uncontrollable deviations in the induction of stem cells differentiation, there are few materials that can currently be translated into clinical applications. In addition to the favorable mechanical properties and biocompatibility of IVD materials, maintaining stem cells activity in the local niche and increasing the ability of stem cells to differentiate into nucleus pulposus (NP) and annulus fibrosus (AF) cells are the basis for promoting the application of IVD-regenerating materials in clinical practice. The purpose of this review is to summarize IVD-regenerating materials that focus on stem cells strategies, analyze the properties of these materials that affect the differentiation of stem cells into IVD-like cells, and then present the limitations of currently used disc materials in the field of stem cell therapy and future research perspectives.

MiR-130a-5p/Foxa2 axis modulates fetal lung development in congenital diaphragmatic hernia by activating the Shh/Gli1 signaling pathway

AIMS

Congenital diaphragmatic hernia (CDH) is a lethal birth defect characterized by congenital lung malformation, and the severity of pulmonary hypoplasia directly affects the prognosis of infants with CDH. Using a nitrofen-induced CDH rat model, we previously reported that Foxa2 expression was downregulated in CDH lungs by proteomics analysis. Here, we investigate the role of miR-130a-5p/Foxa2 axis in lung development of the nitrofen-induced CDH and evaluate its potential role in vivo prenatal therapy.

MAIN METHODS

Nitrofen was orally administrated on embryonic day (E) 8.5 to establish a rat CDH model, and fetal lungs were collected on E13.5, E15.5, E17.5, E19.5 and E21.5. The binding sites of miR-130a-5p on Foxa2 mRNA were identified using bioinformatics prediction software and were validated via luciferase assay. The expression levels of miR-130a-5p and Foxa2 were detected using qRT-PCR, ISH, IHC and western blotting. The role of miR-130a-5p/Foxa2 axis in CDH-associated lung development was investigated in ex vivo lung explants.

KEY FINDINGS

We found that Foxa2 was downregulated in CDH lung tissues, and Foxa2 upregulating improved CDH branching morphogenesis in ex vivo lung explants. Meanwhile, we also showed that miR-130a-5p was significantly upregulated in CDH lungs and thus inversely correlated with Foxa2. Increasing miR-130a-5p abundance with mimics decreases Foxa2-driven Shh/Gli1 signaling and inhibits branching morphogenesis in ex vivo lung explants.

SIGNIFICANCE

This study was the first to show that the miR-130a-5p/Foxa2 axis played a crucial role in CDH-associated pulmonary hypoplasia. These findings may provide relevant insights into the prenatal diagnosis and prenatal therapy of CDH.