Paracrine interaction between adipose-derived stromal cells and cranial suture-derived mesenchymal cells

Aloe polysaccharide promotes osteogenesis potential of adipose-derived stromal cells via BMP-2/Smads and prevents ovariectomized-induced osteoporosis

BACKGROUND

Aloe polysaccharide (AP) is a type of an active macromolecule of Aloe vera, which contributes to its function. However, whether AP possesses anti-osteoporosis properties is unknown.

METHODS

Adipose-derived stromal cells were treated with different concentrations of AP. Early and late osteogenesis were, respectively, evaluated by ALP and Alizarin Red S staining. The effect of AP on the processes of adipogenesis inhibition in ADSCs was analyzed by oil red O staining. Western blot was used to assess the expression of osteogenic and adipogenic related factors. Then, Noggin was administered to further confirm the mechanism by which AP promotes the osteogenesis of ADSCs. Finally, 40 female SD rats were classified into a bilateral laparotomy group (Sham group) and three bilateral ovariectomy groups: OVX group, OVX + AP group, and OVX + AP + Noggin group. The bilateral rat femurs were collected to perform micro-CT scanning, HE, Masson trichrome, and Oil red O staining.

RESULTS

The results indicated that AP could increase ALP expression and calcium deposition. Through molecular mechanisms, AP promotes the protein expression of COL1A1, OPN, and ALP in ADSCs, but downregulates the expression of PPARγ. Also, AP directs ADSCs' fate by stimulating the BMP2/Smads signaling pathway. In vivo, the rat AP-treated had more trabecular bone than the OVX rat, indicating partial protection from cancellous bone loss after treatment with AP.

CONCLUSION

Our results show that AP may promote osteogenesis of ADSCs through BMP-2/Smads signaling pathway and inhibits lipogenic differentiation. Thus, AP might be a promising alternative medicine to treat postmenopausal osteoporosis.

Coordinating Tissue Regeneration Through Transforming Growth Factor-β Activated Kinase 1 Inactivation and Reactivation

Aberrant wound healing presents as inappropriate or insufficient tissue formation. Using a model of musculoskeletal injury, we demonstrate that loss of transforming growth factor-β activated kinase 1 (TAK1) signaling reduces inappropriate tissue formation (heterotopic ossification) through reduced cellular differentiation. Upon identifying increased proliferation with loss of TAK1 signaling, we considered a regenerative approach to address insufficient tissue production through coordinated inactivation of TAK1 to promote cellular proliferation, followed by reactivation to elicit differentiation and extracellular matrix production. Although the current regenerative medicine paradigm is centered on the effects of drug treatment ("drug on"), the impact of drug withdrawal ("drug off") implicit in these regimens is unknown. Because current TAK1 inhibitors are unable to phenocopy genetic Tak1 loss, we introduce the dual-inducible COmbinational Sequential Inversion ENgineering (COSIEN) mouse model. The COSIEN mouse model, which allows us to study the response to targeted drug treatment ("drug on") and subsequent withdrawal ("drug off") through genetic modification, was used here to inactivate and reactivate Tak1 with the purpose of augmenting tissue regeneration in a calvarial defect model. Our study reveals the importance of both the "drug on" (Cre-mediated inactivation) and "drug off" (Flp-mediated reactivation) states during regenerative therapy using a mouse model with broad utility to study targeted therapies for disease. Stem Cells 2019;37:766-778.

Jawbone microenvironment promotes periodontium regeneration by regulating the function of periodontal ligament stem cells

During tooth development, the jawbone interacts with dental germ and provides the development microenvironment. Jawbone-derived mesenchymal stem cells (JBMSCs) maintain this microenvironment for root and periodontium development. However, the effect of the jawbone microenvironment on periodontium tissue regeneration is largely elusive. Our previous study showed that cell aggregates (CAs) of bone marrow mesenchymal stem cells promoted periodontium regeneration on the treated dentin scaffold. Here, we found that JBMSCs enhanced not only the osteogenic differentiation of periodontal ligament stem cells (PDLSCs) but also their adhesion to titanium (Ti) material surface. Importantly, the compound CAs of PDLSCs and JBMSCs regenerated periodontal ligament-like fibers and mineralized matrix on the Ti scaffold surface, both in nude mice ectopic and minipig orthotopic transplantations. Our data revealed that an effective regenerative microenvironment, reconstructed by JBMSCs, promoted periodontium regeneration by regulating PDLSCs function on the Ti material.

Calvarial Defect Healing Induced by Small Molecule Smoothened Agonist

Hedgehog (Hh) signaling positively regulates both endochondral and intramembranous ossification. Use of small molecules for tissue engineering applications poses several advantages. In this study, we examined whether use of an acellular scaffold treated with the small molecule Smoothened agonist (SAG) could aid in critical-size mouse calvarial defect repair. First, we verified the pro-osteogenic effect of SAG in vitro, using primary neonatal mouse calvarial cells (NMCCs). Next, a 4 mm nonhealing defect was created in the mid-parietal bone of 10-week-old CD-1 mice. The scaffold consisted of a custom-fabricated poly(lactic-co-glycolic acid) disc with hydroxyapatite coating (measuring 4 mm diameter × 0.5 mm thickness). Treatment groups included dimethylsulfoxide control (n = 6), 0.5 mM SAG (n = 7) or 1.0 mM SAG (n = 7). Evaluation was performed at 4 and 8 weeks postoperative, by a combination of high-resolution microcomputed tomography, histology (H & E, Masson's Trichrome), histomorphometry, and immunohistochemistry (BSP, OCN, VEGF). In vivo results showed that SAG treatment induced a significant and dose-dependent increase in calvarial bone healing by all radiographic parameters. Histomorphometric analysis showed an increase in all parameters of bone formation with SAG treatment, but also an increase in blood vessel number and density. In summary, SAG is a pro-osteogenic, provasculogenic stimulus when applied locally in a bone defect environment.

Autocrine Sonic hedgehog signaling promotes gastric cancer proliferation through induction of phospholipase Cγ1 and the ERK1/2 pathway

Background

Sonic hedgehog (SHH) plays critical roles in cell growth and development. Tumor cells express SHH, which can promote cell proliferation and epithelial-to-mesenchymal transition. However, the autocrine SHH pathway has not been described in gastric cancer. The aim of this study was to explore molecular mechanisms underlying autocrine SHH signaling in gastric cancer cells.

Methods

SHH expression was assessed using immunohistochemistry and the results were compared with clinicopathologic parameters, including survival. Using gastric cancer cell lines, we measured SHH mRNA and protein expression, and studied the effects of SHH signaling on cell proliferation and SHH secretion. We also studied the effects of an inhibitor of PLC-γ1 on phosphorylation of phospholipase Cγ1 and extracellular signal-regulated kinases (ERK)1/2.

Results

SHH protein expression in gastric cancer tissue was significantly higher compared with that in normal gastric tissue (P < 0.001), and the increased expression was significantly associated with pT staging (P = 0.004), pN staging (P = 0.018), pM staging (P = 0.006), and pTNM staging (P < 0.001). In multivariate analyses, overall survival in gastric cancer was significantly shorter in cases with high SHH expression (HR = 1.734, 95 % CI: 1.109–2.713, P = 0.016). The AGS and SGC-7901 gastric cancer cell lines expressed SHH mRNA and protein. In these cell lines, SHH promoted carcinogenesis through activation of the PLCγ1-ERK1/2 pathway, resulting in increased cell proliferation and survival.

Conclusions

Increased SHH expression is associated with shorter survival in gastric cancer patients, and SHH could represent a useful biomarker or therapeutic target for this disease.

A critical role of autocrine sonic hedgehog signaling in human CD138+ myeloma cell survival and drug resistance

Hedgehog (Hh) signaling plays an important role in the oncogenesis of B-cell malignancies such as multiple myeloma (MM). However, the source of Hh ligand sonic hedgehog (SHH) and its target cells remains controversial. Previous studies showed that stromally induced Hh signaling is essential for the tumor cells and that CD19(+)CD138(-) MM stem cells are the target cells of Hh signaling. Here we demonstrate that SHH was mainly secreted by human myeloma cells but not by stromal cells in MM bone marrow. Autocrine SHH enhanced CD138(+) myeloma cell proliferation and protected myeloma cells from spontaneous and stress-induced apoptosis. More importantly, autocrine SHH protected myeloma cells against chemotherapy-induced apoptosis in vitro and in vivo. Combinational treatment with chemotherapy and SHH-neutralizing antibody displayed synergistic antimyeloma effects. Mechanistic studies showed that SHH signaling activated the SHH/GLI1/BCL-2 axis, leading to the inhibition of myeloma cell apoptosis. Thus, this study identifies the myeloma autocrine Hh signaling pathway as a potential target for the treatment of MM. Targeting this pathway may improve the efficacy of chemotherapy in MM patients.

Adipose-derived mesenchymal stem cells from ventral hernia repair patients demonstrate decreased vasculogenesis

INTRODUCTION

In adipose tissue healing, angiogenesis is stimulated by adipose-derived stromal stem cells (ASCs). Ventral hernia repair (VHR) patients are at high risk for wound infections. We hypothesize that ASCs from VHR patients are less vasculogenic than ASCs from healthy controls.

METHODS

ASCs were harvested from the subcutaneous fat of patients undergoing VHR by the component separation technique and from matched abdominoplasty patients. RNA and protein were harvested on culture days 0 and 3. Both groups of ASCs were subjected to hypoxic conditions for 12 and 24 hours. RNA was analyzed using qRT-PCR, and protein was used for western blotting. ASCs were also grown in Matrigel under hypoxic conditions and assayed for tubule formation after 24 hours.

RESULTS

Hernia patient ASCs demonstrated decreased levels of VEGF-A protein and vasculogenic RNA at 3 days of growth in differentiation media. There were also decreases in VEGF-A protein and vasculogenic RNA after growth in hypoxic conditions compared to control ASCs. After 24 hours in hypoxia, VHR ASCs formed fewer tubules in Matrigel than in control patient ASCs.

CONCLUSION

ASCs derived from VHR patients appear to express fewer vasculogenic markers and form fewer tubules in Matrigel than ASCs from abdominoplasty patients, suggesting decreased vasculogenic activity.

Exploiting paracrine mechanisms of tissue regeneration to repair damaged organs

Stem cells have been studied for many years for their potential to repair damaged organs in the human body. Although many different mechanisms have been suggested as to how stem cells may initiate and facilitate repair processes, much remains unknown. Recently, there has been considerable interest in the idea that stem cells may exert their effects in vivo via paracrine actions. This could involve the release of cytokines, growth factors or secreted extracellular vesicles. This article reviews the role that paracrine actions may play in tissue regeneration. In particular, it considers how microvesicles, as a mediator or modulator of paracrine action, can be exploited as a tool for non-cell-based therapies in regenerative medicine.

Enhancement of human adipose-derived stromal cell angiogenesis through knockdown of a BMP-2 inhibitor

BACKGROUND

Previous studies have demonstrated the role of noggin, a bone morphogenetic protein-2 inhibitor, in vascular development and angiogenesis. The authors hypothesized that noggin suppression in human adipose-derived stromal cells would enhance vascular endothelial growth factor secretion and angiogenesis in vitro and in vivo to a greater extent than bone morphogenetic protein-2 alone.

METHODS

Human adipose-derived stromal cells were isolated from human lipoaspirate (n = 6) noggin was knocked down using lentiviral techniques. Knockdown was confirmed and angiogenesis was assessed by tubule formation and quantitative real-time polymerase chain reaction. Cells were seeded onto scaffolds and implanted into a 4-mm critical size calvarial defect. In vivo angiogenic signaling was assessed by immunofluorescence and immunohistochemistry.

RESULTS

Human adipose-derived stromal cells with noggin suppression secreted significantly higher amounts of angiogenic proteins, expressed higher levels of angiogenic genes, and formed more tubules in vitro. In vivo, calvarial defects seeded with noggin shRNA human adipose-derived stromal cells exhibited a significantly higher number of vessels in the defect site than controls by immunohistochemistry (p < 0.05). In addition, bone morphogenetic protein-2-releasing scaffolds significantly enhanced vascular signaling in the defect site.

CONCLUSIONS

Human adipose-derived stromal cells demonstrate significant increases in angiogenesis in vitro and in vivo with both noggin suppression and BMP-2 supplementation. By creating a cell with noggin suppressed and by using a scaffold with increased bone morphogenetic protein-2 signaling, a more angiogenic niche can be created.

Additive effects of sonic hedgehog and Nell-1 signaling in osteogenic versus adipogenic differentiation of human adipose-derived stromal cells

A theoretical inverse relationship exists between osteogenic (bone forming) and adipogenic (fat forming) mesenchymal stem cell (MSC) differentiation. This inverse relationship in theory partially underlies the clinical entity of osteoporosis, in which marrow MSCs have a preference for adipose differentiation that increases with age. Two pro-osteogenic cytokines have been recently studied that each also possesses antiadipogenic properties: Sonic Hedgehog (SHH) and NELL-1 proteins. In the present study, we assayed the potential additive effects of the biologically active N-terminus of SHH (SHH-N) and NELL-1 protein on osteogenic and adipogenic differentiation of human primary adipose-derived stromal cell (hASCs). We observed that both recombinant SHH-N and NELL-1 protein significantly enhanced osteogenic differentiation and reduced adipose differentiation across all markers examined (alkaline phosphatase, Alizarin red and Oil red O staining, and osteogenic gene expression). Moreover, SHH-N and NELL-1 directed signaling produced additive effects on the pro-osteogenic and antiadipogenic differentiation of hASCs. NELL-1 treatment increased Hedgehog signaling pathway expression; coapplication of the Smoothened antagonist Cyclopamine reversed the pro-osteogenic effect of NELL-1. In summary, Hedgehog and Nell-1 signaling exert additive effects on the pro-osteogenic and antiadipogenic differentiation of ASCs. These studies suggest that the combination cytokines SHH-N+NELL-1 may represent a viable future technique for inducing the osteogenic differentiation of MSCs.

Dura mater stimulates human adipose-derived stromal cells to undergo bone formation in mouse calvarial defects

Human adipose-derived stromal cells (hASCs) have a proven capacity to aid in osseous repair of calvarial defects. However, the bone defect microenvironment necessary for osseous healing is not fully understood. In this study, we postulated that the cell-cell interaction between engrafted ASCs and host dura mater (DM) cells is critical for the healing of calvarial defects. hASCs were engrafted into critical sized calvarial mouse defects. The DM-hASC interaction was manipulated surgically by DM removal or by insertion of a semipermeable or nonpermeable membrane between DM and hASCs. Radiographic, histologic, and gene expression analyses were performed. Next, the hASC-DM interaction is assessed by conditioned media (CM) and coculture assays. Finally, bone morphogenetic protein (BMP) signaling from DM was investigated in vivo using novel BMP-2 and anti-BMP-2/4 slow releasing scaffolds. With intact DM, osseous healing occurs both from host DM and engrafted hASCs. Interference with the DM-hASC interaction dramatically reduced calvarial healing with abrogated BMP-2-Smad-1/5 signaling. Using CM and coculture assays, mouse DM cells stimulated hASC osteogenesis via BMP signaling. Through in vivo manipulation of the BMP-2 pathway, we found that BMP-2 plays an important role in DM stimulation of hASC osteogenesis in the context of calvarial bone healing. BMP-2 supplementation to a defect with disrupted DM allowed for bone formation in a nonhealing defect. DM is an osteogenic cell type that both participates in and stimulates osseous healing in a hASC-engrafted calvarial defect. Furthermore, DM-derived BMP-2 paracrine stimulation appears to play a key role for hASC mediated repair.

Human adipose-derived stromal cells stimulate autogenous skeletal repair via paracrine Hedgehog signaling with calvarial osteoblasts

Human adipose-derived stromal cells (hASCs) have the proven capacity to ossify skeletal defects. The mechanisms whereby hASCs stimulate bone repair are not fully understood. In this study, we examined the potential for hASCs to stimulate autogenous repair of a mouse calvarial defect. Immunofluoresence, osteogenic stains, and surface electron microscopy were used to demonstrate osteogenic differentiation of hASCs. hASCs were engrafted into 4 mm calvarial defects in athymic mice using an osteoconductive scaffold. Analysis included microcomputed tomography, histology, in situ hybridization, and quantitative real-time-polymerase chain reaction. Next, the in vitro interaction between hASCs and mouse calvarial osteoblasts (mOBs) was assessed by the conditioned medium and coculture assays. The medium was supplemented with Hedgehog signaling modifiers, including recombinant N-terminal Sonic hedgehog, smoothened agonist, and cyclopamine. Finally, cyclopamine was delivered in vivo to hASC-engrafted defects. Significant calvarial healing was observed among hASC-engrafted defects compared with control groups (no treatment or scaffold alone) (*P<0.05). hASCs showed evidence of stimulation of host mouse osteogenesis, including (1) increased expression of bone markers at the defect edge by in situ hybridization, and (2) increased host osteogenic gene expression by species-specific quantitative real-time polymerase chain reaction. Using the conditioned medium or coculture assays, hASCs stimulated mOB osteogenic differentiation, accompanied by Hedgehog signaling activation. N-terminal Sonic hedgehog or smoothened agonist replicated, while cyclopamine reversed, the pro-osteogenic effect of the conditioned medium on mOBs. Finally, cyclopamine injection arrested bone formation in vivo. hASCs heal critical-sized mouse calvarial defects, this is, at least in part, via stimulation of autogenous healing of the host defect. Our studies suggest that hASC-derived Hedgehog signaling may play a paracrine role in skeletal repair.