Conditioned medium of demineralized freeze-dried bone activates gene expression in periodontal fibroblasts in vitro

Machine Learning Gene Signature to Metastatic ccRCC Based on ceRNA Network

Clear-cell renal-cell carcinoma (ccRCC) is a silent-development pathology with a high rate of metastasis in patients. The activity of coding genes in metastatic progression is well known. New studies evaluate the association with non-coding genes, such as competitive endogenous RNA (ceRNA). This study aims to build a ceRNA network and a gene signature for ccRCC associated with metastatic development and analyze their biological functions. Using data from The Cancer Genome Atlas (TCGA), we constructed the ceRNA network with differentially expressed genes, assembled nine preliminary gene signatures from eight feature selection techniques, and evaluated the classification metrics to choose a final signature. After that, we performed a genomic analysis, a risk analysis, and a functional annotation analysis. We present an 11-gene signature: SNHG15, AF117829.1, hsa-miR-130a-3p, hsa-mir-381-3p, BTBD11, INSR, HECW2, RFLNB, PTTG1, HMMR, and RASD1. It was possible to assess the generalization of the signature using an external dataset from the International Cancer Genome Consortium (ICGC-RECA), which showed an Area Under the Curve of 81.5%. The genomic analysis identified the signature participants on chromosomes with highly mutated regions. The hsa-miR-130a-3p, AF117829.1, hsa-miR-381-3p, and PTTG1 were significantly related to the patient's survival and metastatic development. Additionally, functional annotation resulted in relevant pathways for tumor development and cell cycle control, such as RNA polymerase II transcription regulation and cell control. The gene signature analysis within the ceRNA network, with literature evidence, suggests that the lncRNAs act as "sponges" upon the microRNAs (miRNAs). Therefore, this gene signature presents coding and non-coding genes and could act as potential biomarkers for a better understanding of ccRCC.

Bone Allograft Acid Lysates Change the Genetic Signature of Gingival Fibroblasts

Bone allografts are widely used as osteoconductive support to guide bone regrowth. Bone allografts are more than a scaffold for the immigrating cells as they maintain some bioactivity of the original bone matrix. Yet, it remains unclear how immigrating cells respond to bone allografts. To this end, we have evaluated the response of mesenchymal cells exposed to acid lysates of bone allografts (ALBA). RNAseq revealed that ALBA has a strong impact on the genetic signature of gingival fibroblasts, indicated by the increased expression of IL11, AREG, C11orf96, STC1, and GK-as confirmed by RT-PCR, and for IL11 and STC1 by immunoassays. Considering that transforming growth factor-β (TGF-β) is stored in the bone matrix and may have caused the expression changes, we performed a proteomics analysis, TGF-β immunoassay, and smad2/3 nuclear translocation. ALBA neither showed detectable TGF-β nor was the lysate able to induce smad2/3 translocation. Nevertheless, the TGF-β receptor type I kinase inhibitor SB431542 significantly decreased the expression of IL11, AREG, and C11orf96, suggesting that other agonists than TGF-β are responsible for the robust cell response. The findings suggest that IL11, AREG, and C11orf96 expression in mesenchymal cells can serve as a bioassay reflecting the bioactivity of the bone allografts.

Osteoinductive and Osteogenic Capacity of Freeze-Dried Bovine Bone Compared to Deproteinized Bovine Bone Mineral Scaffold in Human Umbilical Cord Mesenchymal Stem Cell Culture: An In Vitro Study

OBJECTIVE

 Freeze-dried bovine bone scaffold (FDBB) or decellularized FDBB (dc-FDBB) was developed as an ideal scaffold with osteoinductive properties. This research aims to compare the osteoinductive properties marked by the expression of runt-related transcription factor-2 (RUNX2) and Osterix (OSX) and the osteogenic capacity of these scaffolds imbued with human umbilical cord mesenchymal stem cells (hUCMSCs).

MATERIALS AND METHODS

 This study was performed in five experimental groups: a negative control group (C-) of hUCMSCs with a normal growth medium, a positive control group (C + ) of hUCMSCs with an osteogenic medium, experimental group 1 (E1) with an FDBB conditioned medium (CM), and experimental group 2 (E2) with a dc-FDBB-CM, and a third experimental group (E3) consisting of a DBBM-CM. Alizarin red staining was performed to qualitatively assess osteoinductive capacity. RUNX2 and OSX expression was quantified using real-time quantification polymerase chain reaction with two replications on day six (D6) and day 12 (D12) as fold changes.

RESULTS

 This experiment revealed that hUCMSCs were positively expressed by CD73, CD90, and CD105 but were not expressed by CD34. Alizarin red staining showed that E1 had the most calcium deposition on D6 and D12, followed by E3 and then E2 The RUNX2 and OSX expression was higher in E1 but this difference was not significant. The OSX expression in E1,E2,E3 was lower on D12 and C+ of OSX had the highest expression. There was a significant difference of fold change measured between all groups (p < 0.05), and there was no significant difference between any of the groups treated with OSX and RUNX2 on D6 and D12.

CONCLUSION

 FDBB osteoinduction and osteogenic capacity were higher when compared with DBBM and dc-FDBB.

Functional Properties of a Purified Reconstituted Bilayer Matrix Design Support Natural Wound Healing Activities

Biomaterial engineering has produced numerous matrices for use in tissue repair, utilizing various materials and processing methods, which can impact the ability of the products to encourage wound healing. Recently, we observed favorable clinical outcomes, using a novel purified reconstituted bilayer matrix (PRBM; Geistlich Derma-Gide) to treat chronic diabetic foot ulcers.

Plasma Cell Proliferation Is Reduced in Myeloma-Induced Hypercalcemia and in Co-Culture with Normal Healthy BM-MSCs

OBJECTIVE

In multiple myeloma (MM), stimulation of osteoclasts and bone marrow (BM) lesions lead to hypercalcemia, renal failure, and anemia. Co-culture of the myeloma cells in both hypocalcemia and hypercalcemia concentrations with bone marrow-mesenchymal stem cells were evaluated.

MATERIALS AND METHODS

Viability and survival of myeloma cells were assessed by microculture tetrazolium test and flow cytometric assays. Mesenchymal stem cells (MSCs) were extracted from normal and myeloma patients and were co-cultured with myeloma cells.

RESULTS

Myeloma cells showed less survival in both hypocalcaemia and hypercalcemia conditions (P <.01). The paracrine and juxtacrine conditions of demineralized bone matrix-induced hypercalcemia increased the proliferation and survival of the cells (P <.05). Unlike myeloma MSCs, normal MSCs reduced the survival of and induced apoptosis in myeloma cells (P <.1).

CONCLUSION

Normal healthy-MSCs do not protect myeloma cells, but inhibit them. However, increasing the ratio of myeloma cells to MSCs reduces their inhibitory effects of MSCs and leads to their myelomatous transformation.

Cellular responses to deproteinized bovine bone mineral biofunctionalized with bone-conditioned medium

OBJECTIVES

The aim of the study was to investigate whether the osteoinductive properties of bone-conditioned medium (BCM) harvested from cortical bone chips within a clinically relevant short-term period can enhance the biologic characteristics of deproteinized bovine bone mineral (DBBM) in vitro.

MATERIALS AND METHODS

To assess the biofunctionalization of DBBM, the adhesive, proliferative, and differentiation properties of mesenchymal stromal ST2, pre-osteoblastic MC3T3-E1, and primary bone-derived cells grown on BCM-coated DBBM were examined by crystal violet staining of adherent cells, BrdU ELISA, and qRT-PCR, respectively.

RESULTS

BCM extracted within 20 min or 24 h in either Ringer's solution (BCM-RS) or RS mixed with autologous serum (BCM-RS + S) increased the adhesive properties of all three cell types seeded on DBBM. The 20-min BCM-RS preparation appeared more potent than the 24-h preparation. BCM-RS made within 20 min or 24 h had strong pro-proliferative effects on all cell types grown on DBBM. RS + S alone exhibited a considerable pro-proliferative effect, suggesting an impact of the serum on cellular growth. DBBM coated with BCM-RS or BCM-RS + S, made within 20 min or 24 h each, caused a significant induction of osteogenic differentiation marker expression with a higher potency of the BCM-RS + S. Finally, a strong additive effect of fresh bone chips combined with BCM-coated DBBM on the osteogenic differentiation of the three cell types was observed.

CONCLUSIONS

Altogether, the data strongly support the biofunctionalization of DBBM with BCM extracted within a clinically relevant time window of 20 min.

CLINICAL RELEVANCE

Pre-activation of non-osteoinductive biomaterials with BCM, prepared from autologous bone chips during a guided bone regeneration (GBR) procedure, bears the potential of an optimal treatment modality for bone defects in daily practice.

TGF-β activity in acid bone lysate adsorbs to titanium surface

Objectives

Osteoblasts lay down new bone on implant surfaces. The underlying cellular mechanism and the spatio‐temporal mode of action, however, remain unclear. It can be proposed that growth factors released upon acidification by osteoclasts adsorb to the implant surface and control the early stages of osseointegration.

Methods

To simulate bone lysis by osteoclasts, titanium discs were exposed to acid bone lysate (ABL) followed by vigorous washing and seeding of oral fibroblasts. The expression of TGF‐β target genes interleukin 11 (IL11) and NADPH oxidase 4 (NOX4) was evaluated by reverse transcriptase polymerase chain reaction and IL11 ELISA. TGF‐β signaling activation was assessed via Smad2/3 immunofluorescence. The impact of ABL on osteogenic differentiation was determined with murine ST2 mesenchymal stromal cells.

Results

We report here that ABL‐conditioned titanium discs, independent of turned or rough surface, increased the expression of IL11 and NOX4. This increase was blocked by the TGF‐β receptor 1 antagonist SB431542. Further support for the TGF‐β signaling activation came from the translocation of Smad2/3 into the nucleus of oral fibroblasts. Moreover, titanium discs exposed to ABL decreased alkaline phosphatase and osteopontin in ST2 cells.

Conclusions

These in vitro findings suggest that titanium can adsorb TGF‐β from ABLs. The data provide a strong impetus for studies on the protein adsorption on implant surfaces in vitro and in vivo, specifically for growth factors including bone‐derived TGF‐β during successful and failed osseointegration.

NADPH oxidases in bone homeostasis and osteoporosis

Bone is a tissue with constant remodeling, where osteoblasts form and osteoclasts degrade bone. Both cell types are highly specialized in their function and both form from precursors and have to be replaced on a regular basis. This replacement represents one control level of bone homeostasis. The second important level would be the control of the function of osteoblasts and osteoclasts in order to keep the balance of bone -formation and -degradation. Both differentiation and control of cellular function are potentially redox sensitive processes. In fact, reactive oxygen species (ROS) are utilized by a wide range of cells for differentiation and control of cellular signaling and function. A major source of ROS is the family of NADPH oxidases. The sole function of those enzymes is the formation of ROS in a controlled and targeted manner. Importantly the members of the NADPH oxidase family differ in their localization and in the type and amount of ROS produced. Accordingly the impact of the members of the NADPH oxidase family on differentiation and function differs between cell types. This review will highlight the function of different NADPH oxidases in differentiation and function of bone cells and thereby will discuss the role of NADPH oxidases in bone homeostasis and osteoporosis.

Acid bone lysate activates TGFβ signalling in human oral fibroblasts

Demineralized bone matrix is a widely used allograft from which not only the inorganic mineral but also embedded growth factors are removed by hydrochloric acid (HCl). The cellular response to the growth factors released during the preparation of demineralized bone matrix, however, has not been studied. Here we investigated the in vitro impact of acid bone lysate (ABL) prepared from porcine cortical bone chips on oral fibroblasts. Proteomic analysis of ABL revealed a large spectrum of bone-derived proteins including TGF-β1. Whole genome microarrays and RT-PCR together with the pharmacologic blocking of TGF-β receptor type I kinase with SB431542 showed that ABL activates the TGF-β target genes interleukin 11, proteoglycan 4, and NADPH oxidase 4. Interleukin 11 expression was confirmed at the protein level by ELISA. Immunofluorescence and Western blot showed the nuclear localization of Smad2/3 and increased phosphorylation of Smad3 with ABL, respectively. This effect was independent of whether ABL was prepared from mandible, calvaria or tibia. These results demonstrate that TGF-β is a major growth factor that is removed upon the preparation of demineralized bone matrix.

Bone-conditioned medium contributes to initiation and progression of osteogenesis by exhibiting synergistic TGF-β1/BMP-2 activity

Guided bone regeneration (GBR) often utilizes a combination of autologous bone grafts, deproteinized bovine bone mineral (DBBM), and collagen membranes. DBBM and collagen membranes pre-coated with bone-conditioned medium (BCM) extracted from locally harvested autologous bone chips have shown great regenerative potential in GBR. However, the underlying molecular mechanism remains largely unknown. Here, we investigated the composition of BCM and its activity on the osteogenic potential of mesenchymal stromal cells. We detected a fast and significant (P < 0.001) release of transforming growth factor-β1 (TGF-β1) from autologous bone within 10 min versus a delayed bone morphogenetic protein-2 (BMP-2) release from 40 min onwards. BCMs harvested within short time periods (10, 20, or 40 min), corresponding to the time of a typical surgical procedure, significantly increased the proliferative activity and collagen matrix production of BCM-treated cells. Long-term (1, 3, or 6 days)-extracted BCMs promoted the later stages of osteoblast differentiation and maturation. Short-term-extracted BCMs, in which TGF-β1 but no BMP-2 was detected, reduced the expression of the late differentiation marker osteocalcin. However, when both growth factors were present simultaneously in the BCM, no inhibitory effects on osteoblast differentiation were observed, suggesting a synergistic TGF-β1/BMP-2 activity. Consequently, in cells that were co-stimulated with recombinant TGF-β1 and BMP-2, we showed a significant stimulatory and dose-dependent effect of TGF-β1 on BMP-2-induced osteoblast differentiation due to prolonged BMP signaling and reduced expression of the BMP-2 antagonist noggin. Altogether, our data provide new insights into the molecular mechanisms underlying the favorable outcome from GBR procedures using BCM, derived from autologous bone grafts.

‘Bone-conditioned medium’ could improve oral bone regeneration therapy by promoting the proliferation and maturation of bone-forming cells. Building on recent research demonstrating the benefits of using cell culture medium prepared with bone chips (BCM) in such treatments, researchers led by Maria Asparuhova of the University of Bern, Switzerland, set out to elucidate the medium’s mechanisms. The team found that BCM incubated with bone chips for short periods—as little as ten minutes—contained heightened levels of signaling protein TGF-β1, which enhanced mouse bone marrow cell proliferation while downregulating maturation. BCM incubated for longer periods also generated increased levels of another protein, BMP-2, which boosted the maturation of bone-forming cells. This study reveals a sequential role of these two factors in oral bone development, and the potential physiological actions of BCM when used in regenerative therapies.

High-dose irradiation of bone chips preserves the in vitro activity of bone-conditioned medium

Extracorporeal irradiation sterilizes resected tumor bone used as autografts in reconstruction surgery. Therapeutic irradiation is a standard technique in head and neck cancer therapy that aims to preserve organ function. Bone irradiation has a complex, mostly inhibitory, effect on remodeling and regeneration, although the underlying mechanisms are still not fully understood. It remains unclear if extracorporeal irradiation affects the paracrine-like activity of the corresponding autografts. We recently reported that bone-conditioned medium from autogenous bone chips contains a number of factors that might affect cell activity. In the present study, we investigated the effects of extracorporeal irradiation of porcine cortical bone chips on the activity of the corresponding bone-conditioned medium. The effects of bone-conditioned medium on the expressions of transforming growth factor-beta (TGF-β) target genes in oral fibroblasts were assessed. Bone-conditioned medium from bone chips exposed to a total radiation dose up to 120 Gy did not affect expressions of TGF-β target genes, including adrenomedullin, BTB/POZ domain-containing protein 11, proteoglycan 4, NADPH oxidase 4, and interleukin 11, in oral fibroblasts. In conclusion, bone irradiation does not alter the capability of the corresponding bone-conditioned medium to provoke a robust fibroblastic cell response in vitro. (J Oral Sci 58, 325-331, 2016).

In vitro effects of 0 to 120 Grays of irradiation on bone viability and release of growth factors

BACKGROUND

High dose radiation therapy is commonly used in maxillofacial surgeries to treat a number of head and neck tumors. Despite its widespread use, little information is available regarding the effects of irradiation on bone cell viability and release of growth factors following dose-dependent irradiation.

METHODS

Bone samples were collected from porcine mandibular cortical bone and irradiated at doses of 0, 7.5, 15, 30, 60 and 120 Grays. Thereafter, cell viability was quantified, and the release of growth factors including TGFβ1, BMP2, VEGF, IL1β and RANKL were investigated over time.

RESULTS

It was observed that at only 7.5Gy of irradiation, over 85 % of cells were non-vital and by 60 Gy, all cells underwent apoptosis. Furthermore, over a 7-fold decrease in VEGF and a 2-fold decrease in TGFβ1 were observed following irradiation at all tested doses. Little change was observed for BMP2 and IL1β whereas RANKL was significantly increased for all irradiated samples.

CONCLUSIONS

These results demonstrate the pronounced effects of irradiation on bone-cell vitality and subsequent release of growth factors. Interestingly, the largest observed change in gene expression was the 7-fold decrease in VEGF protein following irradiation. Future research aimed at improving our understanding of bone following irradiation is necessary to further improve future clinical treatments.

Bone conditioned media (BCM) improves osteoblast adhesion and differentiation on collagen barrier membranes

BACKGROUND

The use of autogenous bone chips during guided bone regeneration procedures has remained the gold standard for bone grafting due to its excellent combination of osteoconduction, osteoinduction and osteogenesis. Recent protocols established by our group have characterized specific growth factors and cytokines released from autogenous bone that have the potential to be harvested and isolated into bone conditioned media (BCM). Due to the advantageous osteo-promotive properties of BCM, the aims of the present study was to pre-coat collagen barrier membranes with BCM and investigate its effect on osteoblast adhesion, proliferation and differentiation for possible future clinical use.

METHODS

Scanning electron microscopy (SEM) was first used to qualitative assess BCM protein accumulation on the surface of collagen membranes. Thereafter, undifferentiated mouse ST2 stromal bone marrow cells were seeded onto BioGide porcine derived collagen barrier membranes (control) or barrier membranes pre-coated with BCM (test group). Control and BCM samples were compared for cell adhesion at 8 h, cell proliferation at 1, 3 and 5 days and real-time PCR at 5 days for osteoblast differentiation markers including Runx2, alkaline phosphatase (ALP), osteocalcin (OCN) and bone sialoprotein (BSP). Mineralization was further assessed with alizarin red staining at 14 days post seeding.

RESULTS

SEM images demonstrated evidence of accumulated proteins found on the surface of collagen membranes following coating with BCM. Analysis of total cell numbers revealed that the additional pre-coating with BCM markedly increased cell attachment over 4 fold when compared to cells seeded on barrier membranes alone. No significant difference could be observed for cell proliferation at all time points. BCM significantly increased mRNA levels of osteoblast differentiation markers including ALP, OCN and BSP at 5 days post seeding. Furthermore, barrier membranes pre-coated with BCM demonstrated a 5-fold increase in alizarin red staining at 14 days.

CONCLUSION

The results from the present study suggest that the osteoconductive properties of porcine-derived barrier membranes could be further improved by BCM by significantly increasing cell attachment, differentiation and mineralization of osteoblasts in vitro. Future animal testing is required to fully characterize the additional benefits of BCM for guided bone regeneration.

Pre-coating deproteinized bovine bone mineral (DBBM) with bone-conditioned medium (BCM) improves osteoblast migration, adhesion, and differentiation in vitro

OBJECTIVES

Autogenous bone grafting has remained the gold standard for bone augmentation procedures with ability to release growth factors to the surrounding microenvironment. Recent investigations have characterized these specific growth factors released by autogenous bone chips with further isolation into a "bone-conditioned medium" (BCM). The aim of the present investigation was to utilize autologous growth factors from bone chips (BCM) in combination with deproteinized bovine bone mineral (DBBM) and investigate the ability for BCM to enhance osteoblast behavior.

MATERIALS AND METHODS

Mouse ST2 cells were seeded on (1) DBBM particles alone or (2) DBBM + BCM. Thereafter, samples were compared for cell recruitment, adhesion, proliferation, and real-time PCR for osteoblast differentiation markers including Runx2, collagen 1 alpha 2 (COL1A2), alkaline phosphatase (ALP), and osteocalcin (OCN). Alizarin red staining was used to assess mineralization.

RESULTS

Coating BCM on DBBM particles improved cell migration of ST2 cells and significantly enhanced a 2-fold increase in cell adhesion. While no significant increase in cell proliferation was observed, BCM significantly increased mRNA levels of COL1A2, ALP, and OCN at 3 days post seeding. Furthermore, a 3-fold increase in alizarin red staining was observed on DBBM particles pre-coated with BCM.

CONCLUSION

Pre-coating DBBM with BCM enhanced the osteoconductive properties of DBBM by mediating osteoblast recruitment, attachment, and differentiation towards bone-forming osteoblasts. Future animal study is necessary to further characterize the added benefit of BCM as an autogenous growth factor source for combination therapies.

CLINICAL RELEVANCE

The application of BCM in combination with biomaterials may serve as an autogenous growth factor source for bone regeneration.

Collagen barrier membranes adsorb growth factors liberated from autogenous bone chips

OBJECTIVE

Collagen membranes serve as barriers to separate bone grafts from soft tissues. Bone grafts harvested with a bone scraper release growth factors activating transforming growth factor-β (TGF-β) signaling in mesenchymal cells. The aim of the present pilot study was to determine whether collagen membranes adsorb molecules from bone-conditioned medium (BCM) with the capacity to provoke the expression of TGF-β target genes in vitro.

MATERIALS AND METHODS

Collagen membranes were soaked in aqueous extracts from fresh and demineralized bone chips placed in cell culture medium. Recombinant human TGF-β1 served as control. Gingival fibroblasts were seeded onto the washed collagen membranes and evaluated for the expression of adrenomedullin, pentraxin 3, interleukin 11, and proteoglycan 4. Cell viability and morphology with phalloidin staining were also determined.

RESULTS

Incubation of collagen membranes with BCM for at least one minute caused fibroblasts to decrease the expression of adrenomedullin and pentraxin 3, and to increase the expression of interleukin 11 and proteoglycan 4. Four different membrane treatments - incubated with recombinant TGF-β1, pre-wetted with saline solution, exposed to UV light, and dry out and stored one week at room temperature - also provoked significant changes in gene expression. Likewise, conditioned medium from demineralized bone chips caused gene expression changes. BCM did not alter the viability or morphology of gingival fibroblasts.

CONCLUSIONS

These findings demonstrate that collagen membranes rapidly adsorb the TGF-β activity released from bone chips, a molecular process that might contribute to guided bone regeneration.

Antiseptic solutions modulate the paracrine-like activity of bone chips: differential impact of chlorhexidine and sodium hypochlorite

AIM

Chemical decontamination increases the availability of bone grafts; however, it remains unclear whether antiseptic processing changes the biological activity of bone.

MATERIALS AND METHODS

Bone chips were incubated with four different antiseptic solutions including (1) povidone-iodine (0.5%), (2) chlorhexidine diguluconate (0.2%), (3) hydrogen peroxide (1%) and (4) sodium hypochlorite (0.25%). After 10 min. of incubation, changes in the capacity of the bone-conditioned medium (BCM) to modulate gene expression of gingival fibroblasts was investigated.

RESULTS

Conditioned medium obtained from freshly prepared bone chips increased the expression of TGF-β target genes interleukin 11 (IL11), proteoglycan4 (PRG4), NADPH oxidase 4 (NOX4), and decreased the expression of adrenomedullin (ADM), and pentraxin 3 (PTX3) in gingival fibroblasts. Incubation of bone chips with 0.2% chlorhexidine, followed by vigorously washing resulted in a BCM with even higher expression of IL11, PRG4 and NOX4. These findings were also detected with a decrease in cell viability and an activation of apoptosis signalling. Chlorhexidine alone, at low concentrations, increased IL11, PRG4 and NOX4 expression, independent of the TGF-β receptor I kinase activity. In contrast, 0.25% sodium hypochlorite almost entirely abolished the activity of BCM, whereas the other two antiseptic solutions, 1% hydrogen peroxide and 0.5% povidone-iodine, had relatively no impact respectively.

CONCLUSION

These in vitro findings demonstrate that incubation of bone chips with chlorhexidine differentially affects the activity of the respective BCM compared to the other antiseptic solutions. The data further suggest that the main effects are caused by chlorhexidine remaining in the BCM after repeated washing of the bone chips.