Low doses and high doses of heparin have different effects on osteoblast-like Saos-2 cells in vitro

Lipid and Bone Effects of Heparin Use During Hemodialysis

Unfractionated heparin (UFH) and low-molecular-weight heparins (LMWHs) are commonly prescribed anticoagulants for chronic hemodialysis (HD). The dialysis population comprises a unique group that receives heparin three times per week for a long period, with potential long-term cumulative metabolic effects such as osteoporosis and worsening lipid profile. HD patients have approximately half the number of lipases as healthy individuals, and their lipid metabolism is limited because of this decrease as well as partially inhibited function. Administration of UFH or LMWHs for anticoagulation can lead to metabolic starvation despite high triglyceride levels at the end of HD. In vitro studies indicate that UFH and LMWHs inhibit osteoblasts and promote osteoclasts. In patients on HD, long-term use of UFH or LMWHs did not worsen chronic kidney disease-mineral bone disease. Further investigation is needed to elucidate the underlining mechanisms of UFH and LMWHs and their possible influences on maintenance HD patients.

Synergistic impact of platelet rich plasma-heparin sulfate with hydroxyapatite/zirconia on the osteoblast differentiation potential of adipose-derived mesenchymal stem cells

3D porous hydroxyapatite (HA) has been reinforced by zirconia (ZrO₂) coating and impregnation with a combination of platelet rich plasma (PRP) as a source of growth factors (GFs) and Heparin sulfate (HS) to sustain the release of GFs. Adipose mesenchymal stem cells (ADMSCs) were characterized by flow cytometry for CD (cluster of differentiation) 44, CD105, CD106, CD34 and CD144, along with checking the multipotency by differentiation into the adipocytes and osteoblasts. Then, they were cultured on the scaffold treated with and without osteogenic media on days 7, 14 and 21. Electron micrograph and PKH staining show that the ADMSCs have a fusiform phenotype in the absence of osteogenic induction. Cell viability assay shows a higher number of the viable cells on the PRP-containing scaffolds than PRP-free scaffolds on day 7. Colorimetric evaluation, quantitative RT-PCR and immunocytochemistry demonstrate that PRP and HS significantly elevate the alkaline phosphatase enzyme activity and also accelerate the production of both early and mid-osteogenic markers, including collagen I and osteopontin expression with and without osteogenic conditions. The PRP-HS also accelerates the expression of the late osteogenic marker, osteocalcin, in both mRNA and protein level expression with a peak on day 21. In conclusion, supplementation of HA/ZrO₂ with PRP/HS has a synergistic impact on the ADMSCs, even in the absence of chemical induction. It seems that HA/ZrO₂/PRP/HS scaffold provides a higher osteoconductive microenvironment for stem cell differentiation to osteoblasts.

Mast cell and heparin promote adipogenesis in superficial fascia of rats

Fascial adipocytes are recently identified as a unique population of adipose cells, which have different developmental origins, anatomical locations, cytological and functional characteristics compared with subcutaneous or visceral adipocytes. Superficial fascia in rats (also in pigs but not obviously in mice) contains numbers of lineage committed preadipocytes which possess adipogenic potential in vivo. The present study aimed to investigate the physiological factors that contribute to fascial adipogenesis in rats. We detected that mast cells, adipose progenitor cells, and mature adipocytes distributed in certain fascia areas were closely associated with each other, and numerous heparin-loaded granules released from mast cells were distributed around fascial preadipocytes. The culture supernatants of rat peritoneal mast cells and RBL-2H3 mast cells contained 20-30 μg/ml of heparin, effectively activated PPAR-responsive luciferase activity, promoted mRNA and protein expressions of key adipogenic genes, and hence increased adipogenic differentiation of fascia- or epididymal adipose-derived stromal cells. Adipogenic effects of mast cell supernatants were mimicked by heparin but not by histamine or 5-hydroxytryptamine, and were antagonized by protamine sulfate. Adipogenic effects of heparin may relate to its chain length of glucosamine units, because heparin stimulated stronger adipogenesis than dalteparin and enoxaparin with relatively short chains. In rats, local administration of heparin-loaded microspheres for 30 days induced adipogenesis in local areas of superficial fascia. Our findings suggested that mast cell and its granule heparin could serve as the endogenous physiological factors to initiate and accelerate local adipogenesis in superficial fascia, or in adipose tissue with the fascia naturally embedded inside.

A Blood Bank Standardized Production of Human Platelet Lysate for Mesenchymal Stromal Cell Expansion: Proteomic Characterization and Biological Effects

Human platelet lysate (hPL) is considered a valid substitute to fetal bovine serum (FBS) in the expansion of mesenchymal stromal cells (MSC), and it is commonly produced starting from intermediate side products of whole blood donations. Through freeze-thaw cycles, hPL is highly enriched in chemokines, growth factors, and adhesion and immunologic molecules. Cell therapy protocols, using hPL instead of FBS for the expansion of cells, are approved by regulatory authorities without concerns, and its administration in patients is considered safe. However, published data are fairly difficult to compare, since the production of hPL is highly variable. This study proposes to optimize and standardize the hPL productive process by using instruments, technologies, and quality/safety standards required for blood bank activities and products. The quality and improved selection of the starting material (i.e., the whole blood), together with the improvement of the production process, guarantee a product characterized by higher content and quality of growth factors as well as a reduction in batch-to-batch variability. By increasing the number of freeze/thaw cycles from one (hPL1c) to four (hPL4c), we obtained a favorable effect on the release of growth factors from platelet α granules. Those changes have directly translated into biological effects leading to a decreasing doubling time (DT) of MSC expansion at 7 days (49.41 ± 2.62 vs. 40.61 ± 1.11 h, p < 0.001). Furthermore, mass spectrometry (MS)-based evaluation has shown that the proliferative effects of hPL4c are also combined with a lower batch-to-batch variability (10-15 vs. 21-31%) at the proteomic level. In conclusion, we have considered lot-to-lot hPL variability, and by the strict application of blood bank standards, we have obtained a standardized, reproducible, safe, cheap, and ready-to-use product.

Antiproliferative Properties of Scandium Exopolysaccharide Complexes on Several Cancer Cell Lines

Antimetastatic properties on both murine and human osteosarcoma cell lines (POS-1 and KHOS) have been evidenced using exopolysaccharide (EPS) derivatives, produced by Alteromonas infernus bacterium. These derivatives had no significant effect on the cell cycle neither a pro-apoptotic effect on osteosarcoma cells. Based on this observation, these EPSs could be employed as new drug delivery systems for therapeutic uses. A theranostic approach, i.e., combination of a predictive biomarker with a therapeutic agent, has been developed notably by combining with true pair of theranostic radionuclides, such as scandium ⁴⁷Sc/⁴⁴Sc. However, it is crucial to ensure that, once complexation is done, the biological properties of the vector remain intact, allowing the molecular tropism of the ligand to recognize its molecular target. It is important to assess if the biological properties of EPS evidenced on osteosarcoma cell lines remain when scandium is complexed to the polymers and can be extended to other cancer cell types. Scandium-EPS complexes were thus tested in vitro on human cell lines: MNNG/HOS osteosarcoma, A375 melanoma, A549 lung adenocarcinoma, U251 glioma, MDA231 breast cancer, and Caco2 colon cancer cells. An xCELLigence Real Cell Time Analysis (RTCA) technology assay was used to monitor for 160 h, the proliferation kinetics of the different cell lines. The tested complexes exhibited an anti-proliferative effect, this effect was more effective compared to EPS alone. This increase of the antiproliferative properties was explained by a change in conformation of EPS complexes due to their polyelectrolyte nature that was induced by complexation. Alterations of both growth factor-receptor signaling, and transmembrane protein interactions could be the principal cause of the antiproliferative effect. These results are very promising and reveal that EPS can be coupled to scandium for improving its biological effects and also suggesting that no major structural modification occurs on the ligand.

Long-chain polyphosphate in osteoblast matrix vesicles: Enrichment and inhibition of mineralization

BACKGROUND

Inorganic polyphosphate (polyP) is a fundamental and ubiquitous molecule in prokaryotes and eukaryotes. PolyP has been found in mammalian tissues with particularly high levels of long-chain polyP in bone and cartilage where critical questions remain as to its localization and function. Here, we investigated polyP presence and function in osteoblast-like SaOS-2 cells and cell-derived matrix vesicles (MVs), the initial sites of bone mineral formation.

METHODS

PolyP was quantified by 4',6-diamidino-2-phenylindole (DAPI) fluorescence and characterized by enzymatic methods coupled to urea polyacrylamide gel electrophoresis. Transmission electron microscopy and confocal microscopy were used to investigate polyP localization. A chicken embryo cartilage model was used to investigate the effect of polyP on mineralization.

RESULTS

PolyP increased in concentration as SaOS-2 cells matured and mineralized. Particularly high levels of polyP were observed in MVs. The average length of MV polyP was determined to be longer than 196 P_i residues by gel chromatography. Electron micrographs of MVs, stained by two polyP-specific staining approaches, revealed polyP localization in the vicinity of the MV membrane. Additional extracellular polyP binds to MVs and inhibits MV-induced hydroxyapatite formation.

CONCLUSION

PolyP is highly enriched in matrix vesicles and can inhibit apatite formation. PolyP may be hydrolysed to phosphate for further mineralization in the extracellular matrix.

GENERAL SIGNIFICANCE

PolyP is a unique yet underappreciated macromolecule which plays a critical role in extracellular mineralization in matrix vesicles.

Novel pH-responsive tobramycin-embedded micelles in nanostructured multilayer-coatings of chitosan/heparin with efficient and sustained antibacterial properties

To endow orthopaedic implants with satisfactory antibacterial properties, the design and development of antibiotic coating on the surface of implants is highly desired. In this work a novel and facile strategy was developed to form pH-responsive layer-by-layer (LbL) films implanted with polymeric micelles as nano-vehicles loaded with charge-weak antibiotic drugs, enabling high drug loading efficiency. Negatively charged tobramycin (Tob)-embeded heparin miscells (HET) and positively charged chitosan (CHT) were exploited as a pH-responsive LBL multilayer building block, respectively. The formation mechanism and pH-stimulated release behavior of the Tob-contained heparin micelles were studied. The characterization on the morphologies, chemical compositions and hydrophilicity of the modified surface confirmed the successuful deposition of the Tob-loaded CHT/HET multilayers coatings on the polydopamine-modified Ti surface. The drug release profiles displayed fast release at pH 7.4 and slow release after exposure to weakly acidic environments. Antibacterial tests indicated that the Tob-embed CHT/HET nanostructured multilayers not only strongly inhibited initial bacterial adhesion, but also disruptted biofilm formation. Particularly, this functional coatings showed "long-term antibacterial" pattern in acid condition. Meanwhile, MC3T3 cells showed acceptable adhesion, spread and proliferation on the multilayer coatings in cytocompatible studies. In a word, these multilayer coatings incorporated with a wide variety of antibiotics show promisiong applications in preventing postoperative infection and resolving unmet clinical need.

Surface modification of porous alpha-tricalcium phosphate granules with heparin enhanced their early osteogenic capability in a rat calvarial defect model

Heparin binds to and modulates various growth factors, potentially augmenting the bone-forming capability of biomaterials. Here, α-tricalcium phosphate (α-TCP) granules were modified with peptide containing the marine mussel-derived adhesive sequence, which reacts with α-TCP surface, and cationic sequence, which binds to heparin (α-Ph). α-Ph retained the α-TCP phase and intergranule spaces after the surface modification. The existence of heparin on α-Ph granules was confirmed using X-ray photoelectron spectroscopy. Granules of α-TCP and α-Ph were implanted into critical-size defects in rat calvaria for 4 weeks. Micro-computed tomography, histological evaluation, and Alcian blue staining revealed that α-Ph induced superior bone formation compared with α-TCP. Newly formed bone on α-Ph was preferentially in contact with the Alcian blue-stained surfaces of granules. These results suggested that heparinization enhanced the early osteogenic capacity of α-TCP, possibly by modulating the secretion of Alcian blue-stained extracellular matrixes.

Presentation of functional groups on self-assembled supramolecular peptide nanofibers mimicking glycosaminoglycans for directed mesenchymal stem cell differentiation

Organizational complexity and functional diversity of the extracellular matrix regulate cellular behaviors.

Heparin affects human bone marrow stromal cell fate: Promoting osteogenic and reducing adipogenic differentiation and conversion

Heparins are broadly used for the prevention and treatment of thrombosis and embolism. Yet, osteoporosis is considered to be a severe side effect in up to one third of all patients on long-term treatment. However, the mechanisms underlying this clinical problem are only partially understood. To investigate if heparin affects differentiation of skeletal precursors, we examined the effects of heparin on the osteogenic and adipogenic lineage commitment and differentiation of primary human bone marrow stromal cells (hBMSCs). Due to the known inverse relationship between adipogenesis and osteogenesis and the capacity of pre-differentiated cells to convert into the respective other lineage, we also determined heparin effects on osteogenic conversion and adipogenic differentiation/conversion. Interestingly, heparin did not only significantly increase mRNA expression and enzyme activity of the osteogenic marker alkaline phosphatase (ALP), but it also promoted mineralization during osteogenic differentiation and conversion. Furthermore, the mRNA expression of the osteogenic marker bone morphogenic protein 4 (BMP4) was enhanced. In addition, heparin administration partly prevented adipogenic differentiation and conversion demonstrated by reduced lipid droplet formation along with a decreased expression of adipogenic markers. Moreover, luciferase reporter assays, inhibitor experiments and gene expression analyses revealed that heparin had putative permissive effects on osteogenic signaling via the BMP pathway and reduced the mRNA expression of the Wnt pathway inhibitors dickkopf 1 (DKK1) and sclerostin (SOST). Taken together, our data show a rather supportive than inhibitory effect of heparin on osteogenic hBMSC differentiation and conversion in vitro. Further studies will have to investigate the net effects of heparin administration on bone formation versus bone resorption in vivo to unravel the molecular mechanisms of heparin-associated osteoporosis and reconcile conflicting experimental data with clinical observations.

Heparin microparticle effects on presentation and bioactivity of bone morphogenetic protein-2

Biomaterials capable of providing localized and sustained presentation of bioactive proteins are critical for effective therapeutic growth factor delivery. However, current biomaterial delivery vehicles commonly suffer from limitations that can result in low retention of growth factors at the site of interest or adversely affect growth factor bioactivity. Heparin, a highly sulfated glycosaminoglycan, is an attractive growth factor delivery vehicle due to its ability to reversibly bind positively charged proteins, provide sustained delivery, and maintain protein bioactivity. This study describes the fabrication and characterization of heparin methacrylamide (HMAm) microparticles for recombinant growth factor delivery. HMAm microparticles were shown to efficiently bind several heparin-binding growth factors (e.g. bone morphogenetic protein-2 (BMP-2), vascular endothelial growth factor (VEGF), and basic fibroblast growth factor (FGF-2)), including a wide range of BMP-2 concentrations that exceeds the maximum binding capacity of other common growth factor delivery vehicles, such as gelatin. BMP-2 bioactivity was assessed on the basis of alkaline phosphatase (ALP) activity induced in skeletal myoblasts (C2C12). Microparticles loaded with BMP-2 stimulated comparable C2C12 ALP activity to soluble BMP-2 treatment, indicating that BMP-2-loaded microparticles retain bioactivity and potently elicit a functional cell response. In summary, our results suggest that heparin microparticles stably retain large amounts of bioactive BMP-2 for prolonged periods of time, and that presentation of BMP-2 via heparin microparticles can elicit cell responses comparable to soluble BMP-2 treatment. Consequently, heparin microparticles present an effective method of delivering and spatially retaining growth factors that could be used in a variety of systems to enable directed induction of cell fates and tissue regeneration.

Ursodeoxycholic acid increases differentiation and mineralization and neutralizes the damaging effects of bilirubin on osteoblastic cells

BACKGROUND

Osteoporosis resulting from decreased bone formation is a common complication in patients with chronic cholestasis. Lithocholic acid (LCA) and bilirubin may play a role in osteoporosis given that both substances have detrimental effects on survival of human osteoblasts, the cells involved in bone formation.

AIMS

As ursodeoxycholic acid (UDCA) improves cholestasis, we have assessed if this bile acid may neutralize the harmful effects of LCA, bilirubin and sera from jaundiced patients on osteoblastic cells.

METHODS

The experiments were performed in primary human osteoblasts and human osteosarcoma cell line (Saos-2) at different times and concentrations of UDCA, LCA, cholic acid (CA), bilirubin and sera from jaundiced patients to assess cell viability, differentiation and mineralization.

RESULTS

UDCA significantly decreased cell survival at concentrations 10 times higher (1 mM) than that observed with LCA, whereas CA did not decrease osteoblast survival. UDCA (100 μM) neutralized the damaging effects of bilirubin (50 μM) and sera from jaundiced patients on survival. Moreover, UDCA (1 μM and 10 μM) increased osteoblast differentiation in cells treated with harmful concentrations of LCA or bilirubin. UDCA (100 μM) increased cell differentiation in osteoblasts cultured with a mix of serum from cholestatic patients by 23%. Furthermore, UDCA increased osteoblast mineralization by 35% and neutralized the negative consequences of 50 μM bilirubin.

CONCLUSIONS

UDCA increases osteoblast differentiation and mineralization, and neutralizes the detrimental effects of lithocholic acid, bilirubin and sera from jaundiced patients on osteoblastic cells. Therefore, UDCA may exert a favourable effect on bone in patients which chronic cholestasis.

Heparin concentration is critical for cell culture with human platelet lysate

BACKGROUND AIMS

Culture media for mesenchymal stromal cells (MSCs) are generally supplemented with fetal bovine serum. Human platelet lysate (hPL) has been proven to be a very effective alternative without the risk of xenogeneic infections or immune reactions. In contrast to fetal bovine serum, hPL comprises plasma, and anticoagulants-usually unfractionated heparin (UFH)-need to be added to prevent gel formation.

METHODS

Cultures of MSCs in hPL media with various concentrations of UFH and enoxaparin, a low-molecular-weight heparin (LMWH), were systematically compared with regard to proliferation, fibroblastoid colony-forming unit frequency, immunophenotype and in vitro differentiation.

RESULTS

At least 0.61 IU/mL UFH or 0.024 mg/mL LMWH was necessary for reliable prevention of coagulation of hPL pools used in this study. Higher concentrations impaired cellular proliferation in a dose-dependent manner even without benzyl alcohol, which is commonly added to heparins as a bacteriostatic agent. Colony-forming unit frequency was also reduced at higher heparin concentrations, particularly with LMWH, whereas no significant effect was observed on cellular morphology or immunophenotype. High concentrations of heparins reduced the in vitro differentiation toward adipogenic and osteogenic lineages.

CONCLUSIONS

Heparin concentration is critical for culture of MSCs in hPL media; this is of particular relevance for cellular therapy where cell culture procedures need to be optimized and standardized.

Enhanced control of in vivo bone formation with surface functionalized alginate microbeads incorporating heparin and human bone morphogenetic protein-2

In this study, we tested the hypothesis that a surface functionalization delivery platform incorporating heparin onto strontium alginate microbeads surfaces would convert this "naive carriers" into "mini-reservoirs" for localized in vivo delivery of recombinant human bone morphogenetic protein-2 (rhBMP-2) that will induce functional bone regeneration. In vitro evaluation confirmed that (1) heparin incorporation could immobilize and prolong rhBMP-2 release for approximately 3 weeks; (2) a significant decrease (p<0.01) in rhBMP-2 burst release is attainable depending on initial protein load; and (3) rhBMP-2 released from surface functionalized microbeads retained bioactivity and stimulated higher alkaline phosphatase activity in cultured C(2)C(12) cells when compared with daily administration of fresh bolus rhBMP-2. Subsequently, surface functionalized microbeads were used for in vivo delivery of rhBMP-2 at local sites of posterolateral spinal fusion surgery in rats. The microbeads were loaded into the pores of medical-grade polyepsilone caprolactone-tricalcium phosphate scaffolds before implantation. Results revealed robust bone formation and a biomechanically solid fusion after 6 weeks. When compared with a control group consisting of an equivalent amount of rhBMP-2 that was directly adsorbed onto bare-surfaced microbeads with no heparin, a 5.3-fold increase in bone volume fraction and a 2.6-fold increase in bending stiffness (flexion/extension) were observed. When compared with collagen sponge carriers of rhBMP-2, a 1.5-fold and a 1.3-fold increase in bone volume fraction and bending stiffness were observed, respectively. More importantly, 3D micro-computed tomography images enabled the visualization of a well-contained newly formed bone at ipsilateral implant sites with surface functionalized rhBMP-2 delivery. This was absent with collagen sponge carriers where newly formed bone tissue was poorly contained and crossed over the posterior midline to contralateral implants. These findings are important because of complications with current rhBMP-2 delivery method, including excessive, uncontrolled bone formation.

The effects of direct factor Xa inhibitor (Rivaroxaban) on the human osteoblastic cell line SaOS2

Thromboprophylaxis reduces the risk of surgery-related deep vein thrombosis, but anticoagulants were associated with systemic osteoporosis, a known risk factor for poor fracture healing. Rivaroxaban (XARELTO(®)) is a novel anticoagulant with specific ability to inhibit factor Xa, a serine endopeptidase, which plays a key role in coagulation. This study investigated the direct effects of rivaroxaban on bone biology using an in vitro cell culture model from the human female osteoblastic cell line SaOS2. Cells at subconfluence were treated for 24 hr with different concentrations of rivaroxaban and analyzed for DNA synthesis and creatine kinase- and alkaline phosphatase-specific activities, and were treated 21 days for analyzing mineralization. Rivaroxaban (0.01-50 μg/ml) dose-dependently inhibited up to 60% DNA synthesis of the cells. Creatine kinase-specific activity was also inhibited dose-dependently to a similar extent by the same concentrations. Alkaline phosphatase-specific activity was dose-dependently inhibited but only up to 30%. Cell mineralization was unaffected by 10 μg/ml rivaroxaban. This model demonstrated a significant rivaroxaban-induced reduction in osteoblastic cell growth and energy metabolism, and slight inhibition of the osteoblastic marker, alkaline phosphatase, while osteoblastic mineralization was unaffected. These findings might indicate that rivaroxaban inhibits the first stage of bone formation but does not affect later stages (i.e., bone mineralization).

Glycosaminoglycans enhance osteoblast differentiation of bone marrow derived human mesenchymal stem cells

Extracellular matrix plays an important role in regulating cell growth and differentiation. The biomimetic approach of cell-based tissue engineering is based on mirroring this in vivo micro environment for developing a functional tissue engineered construct. In this study, we treated normal tissue culture plates with selected extracellular matrix components consisting of glycosaminoglycans such as chondroitin-4-sulphate, dermatan sulphate, chondroitin-6-sulphate, heparin and hyaluronic acid. Mesenchymal stem cells isolated from adult human bone marrow were cultured on the glycosaminoglycan treated culture plates to evaluate their regulatory role in cell growth and osteoblast differentiation. Although no significant improvement on human mesenchymal stem cell adhesion and proliferation was observed on the glycosaminoglycan-treated tissue culture plates, there was selective osteoblast differentiation, indicating its potential role in differentiation rather than proliferation. Osteoblast differentiation studies showed high osteogenic potential for all tested glycosaminoglycans except chondroitin-4-sulphate. Osteoblast differentiation-associated genes such as osterix, osteocalcin, integrin binding sialoprotein, osteonectin and collagen, type 1, alpha 1 showed significant upregulation. We identified osterix as the key transcription factor responsible for the enhanced bone matrix deposition observed on hyaluronic acid, heparin and chondroitin-6-sulphate. Hyaluronic acid provided the most favourable condition for osteoblast differentiation and bone matrix synthesis. Our results confirm and emphasise the significant role of extracellular matrix in regulating cell differentiation. To summarise, glycosaminoglycans of extracellular matrix played a significant role in regulating osteoblast differentiation and could be exploited in the biomimetic approach of fabricating or functionalizing scaffolds for stem cell based bone tissue engineering.

Bone marrow-derived heparan sulfate potentiates the osteogenic activity of bone morphogenetic protein-2 (BMP-2)

Lowering the efficacious dose of bone morphogenetic protein-2 (BMP-2) for the repair of critical-sized bone defects is highly desirable, as supra-physiological amounts of BMP-2 have an increased risk of side effects and a greater economic burden for the healthcare system. To address this need, we explored the use of heparan sulfate (HS), a structural analog of heparin, to enhance BMP-2 activity. We demonstrate that HS isolated from a bone marrow stromal cell line (HS-5) and heparin each enhances BMP-2-induced osteogenesis in C2C12 myoblasts through increased ALP activity and osteocalcin mRNA expression. Commercially available HS variants from porcine kidney and bovine lung do not generate effects as great as HS5. Heparin and HS5 influence BMP-2 activity by (i) prolonging BMP-2 half-life, (ii) reducing interactions between BMP-2 with its antagonist noggin, and (iii) modulating BMP2 distribution on the cell surface. Importantly, long-term supplementation of HS5 but not heparin greatly enhances BMP-2-induced bone formation in vitro and in vivo. These results show that bone marrow-derived HS effectively supports bone formation, and suggest its applicability in bone repair by selectively facilitating the delivery and bioavailability of BMP-2.

Differentiation of mesenchymal stem cells in heparin-containing hydrogels via coculture with osteoblasts

The therapeutic potency of delivered mesenchymal stem cells (MSCs) in tissue engineering applications may be improved by priming cells toward a differentiated state via coculture with native, differentiated cells prior to implantation; however, there is a lack of understanding in what may be the most efficacious method. The objective of this study was to investigate the role of negatively-charged heparin in priming hydrogel-encapsulated MSCs toward the osteoblastic lineage during coculture with a monolayer of osteoblasts in the absence of dexamethasone. MSCs encapsulated with higher amounts of heparin and cocultured with osteoblasts exhibited an over 36-fold increase in alkaline phosphatase activity and 13-fold increase in calcium accumulation by day 21, compared to MSCs cocultured with MSCs at the same heparin content. Moreover, hydrogels with higher amounts of heparin and cocultured with osteoblasts exhibited enhanced mineralization on the edges, suggesting that heparin may be important in sequestering osteoblast-secreted soluble factors, particularly on the surfaces of hydrogels. The ability of heparin to selectively interact with soluble positively-charged proteins from the surroundings was confirmed through protein labeling and microscopy. These results suggest that heparin-containing hydrogels as part of a coculture system can be utilized as a versatile platform to study and enhance priming of MSCs toward various cell types for a wide variety of regenerative medicine-based therapies.

The influence of low molecular weight heparin on the expression of osteogenic growth factors in human fracture healing

PURPOSE

Anticoagulant therapy with low molecular weight heparins (LMWH) and mechanical compression is considered the gold standard for the prevention of thrombosis. However, evidence exists that LMWHs impair bone metabolism. The aim of this study was therefore to analyse alterations in the expression of M-CSF, VEGF and TGF-ß1 after treatment with enoxaparin in patients with long bone fracture to investigate the effect of LMWH on human fracture healing.

METHODS

A total of 81 patients with long bone fractures were included in the study and divided into two groups. One group comprised patients who received enoxaparin and the other group, patients who did not receive enoxaparin postoperatively. Growth factor levels were analysed in patients' serum and different groups were retrospectively compared.

RESULTS

M-CSF serum concentrations were found to be significantly higher only at 48 weeks after surgery in enoxaparin. Mean overall VEGF serum concentration was higher in patients with enoxaparin. TGF-β1 serum concentrations were higher at 48 weeks after surgery in patients with enoxaparin.

CONCLUSION

This is the first comparative systemic measurement of M-CSF, VEGF and TGF-ß1 serum levels in patients with and without enoxaparin after long bone fracture. Significant differences of the expression of the growth factors after enoxaparin therapy were only observed at week 48 after surgery for M-CSF and TGF-ß1.

Fibroblast growth factor 23 (FGF23) and alpha-klotho stimulate osteoblastic MC3T3.E1 cell proliferation and inhibit mineralization

Elevated serum levels of the phosphate-regulating hormone fibroblast growth factor 23 (FGF23) are found in patients with phosphate wasting diseases and chronic kidney disease-mineral and bone disorder (CKD-MBD). These diseases are associated with rickets and renal osteodystrophy, respectively. FGF23 is secreted from osteoblastic cells and signals through FGFRs, membrane coreceptor alpha-Klotho (Klotho), and, possibly, a circulating form of Klotho. Despite the absence of detectable Klotho on osteoblastic cells, studies have suggested that forced FGF23 expression in osteoblasts inhibited mineralization. Thus, we examined the effects of exogenously applied FGF23 on osteoblastic MC3T3.E1 cell proliferation and differentiation, with and without soluble Klotho. MC3T3.E1 cells were cultured in osteoblast differentiation medium, supplemented with FGF23 (0.1-1,000 ng/mL), Klotho (50 ng/mL), the combination FGF23 + Klotho, and FGF2 (100 ng/mL) as a control. Neither FGF23 nor Klotho exposure affected proliferation of day 4 growth phase cells or mineralization of day 14 cultures. In contrast, FGF23 + Klotho resulted in inhibition of mineralization and osteoblast activity markers at day 14, and a slight, reproducible induction of proliferation. Inhibition of FGFR1, but not FGFR2 or FGFR3, completely restored FGF23 + Klotho-induced inhibition of alkaline phosphatase (ALP) activity at day 7. ALP activity was partially restored by the MAPK inhibitor U0126 but not inhibitors p38 and P13K. Thus, soluble Klotho enables FGF23 signaling in MC3T3.E1 cells, likely through FGFR 1(IIIc). Elevated FGF23 actions, in part, appear to parallel FGF2 with lower potency. In addition to affecting bone via indirect phosphate wasting pathways, supraphysiological FGF23 and soluble Klotho may directly impact bone in diseases with elevated FGF23 levels.

Proteomic characterization of biogenesis and functions of matrix vesicles released from mineralizing human osteoblast-like cells

Matrix vesicles (MVs), released by budding from apical microvilli of osteoblasts during bone formation and development, are involved in the initiation of mineralization by promoting the formation of hydroxyapatite in their lumen. To gain additional insights into MV biogenesis and functions, MVs and apical microvilli were co-isolated from mineralizing osteoblast-like Saos-2 cells and their proteomes were characterized using LC-ESI-MS/MS and compared. In total, 282 MV and 451 microvillar proteins were identified. Of those, 262 were common in both preparations, confirming that MVs originate from apical microvilli. The occurrence of vesicular trafficking molecules (e.g. Rab proteins) and of the on-site protein synthetic machinery suggests that cell polarization and apical targeting are required for the incorporation of specific lipids and proteins at the site of MV formation. MV release from microvilli may be driven by actions of actin-severing proteins (gelsolin, cofilin 1) and contractile motor proteins (myosins). In addition to the already known proteins involved in MV-mediated mineralization, new MV residents were detected, such as inorganic pyrophosphatase 1, SLC4A7 sodium bicarbonate cotransporter or sphingomyelin phosphodiesterase 3, providing additional insights into MV functions.

Heparin: a potent inhibitor of hepcidin expression in vitro and in vivo

Hepcidin is a major regulator of iron homeostasis, and its expression in liver is regulated by iron, inflammation, and erythropoietic activity with mechanisms that involve bone morphogenetic proteins (BMPs) binding their receptors and coreceptors. Here we show that exogenous heparin strongly inhibited hepcidin expression in hepatic HepG2 cells at pharmacologic concentrations, with a mechanism that probably involves bone morphogenetic protein 6 sequestering and the blocking of SMAD signaling. Treatment of mice with pharmacologic doses of heparin inhibited liver hepcidin mRNA expression and SMAD phosphorylation, reduced spleen iron concentration, and increased serum iron. Moreover, we observed a strong reduction of serum hepcidin in 5 patients treated with heparin to prevent deep vein thrombosis, which was accompanied by an increase of serum iron and a reduction of C-reactive protein levels. The data show an unrecognized role for heparin in regulating iron homeostasis and indicate novel approaches to the treatment of iron-restricted iron deficiency anemia.

Functionalization of chitosan/poly(lactic acid-glycolic acid) sintered microsphere scaffolds via surface heparinization for bone tissue engineering

Scaffolds exhibiting biological recognition and specificity play an important role in tissue engineering and regenerative medicine. The bioactivity of scaffolds in turn influences, directs, or manipulates cellular responses. In this study, chitosan/poly(lactic acid-co-glycolic acid) (chitosan/PLAGA) sintered microsphere scaffolds were functionalized via heparin immobilization. Heparin was successfully immobilized on chitosan/PLAGA scaffolds with controllable loading efficiency. Mechanical testing showed that heparinization of chitosan/PLAGA scaffolds did not significantly alter the mechanical properties and porous structures. In addition, the heparinized chitosan/PLAGA scaffolds possessed a compressive modulus of 403.98 +/- 19.53 MPa and a compressive strength of 9.83 +/- 0.94 MPa, which are in the range of human trabecular bone. Furthermore, the heparinized chitosan/PLAGA scaffolds had an interconnected porous structure with a total pore volume of 30.93 +/- 0.90% and a median pore size of 172.33 +/- 5.89 mum. The effect of immobilized heparin on osteoblast-like MC3T3-E1 cell growth was investigated. MC3T3-E1 cells proliferated three dimensionally throughout the porous structure of the scaffolds. Heparinized chitosan/PLAGA scaffolds with low heparin loading (1.7 microg/scaffold) were shown to be capable of stimulating MC3T3-E1 cell proliferation by MTS assay and cell differentiation as evidenced by elevated osteocalcin expression when compared with nonheparinized chitosan/PLAGA scaffold and chitosan/PLAGA scaffold with high heparin loading (14.1 microg/scaffold). This study demonstrated the potential of functionalizing chitosan/PLAGA scaffolds via heparinization with improved cell functions for bone tissue engineering applications.

Porcine bone marrow stromal cell differentiation on heparin-adsorbed poly(e-caprolactone)-tricalcium phosphate-collagen scaffolds

We evaluate the potential of heparin as a substrate component for the fabrication of bone tissue engineering constructs using poly(e-caprolactone)-tricalcium phosphate-collagen type I (PCL-TCP-Col) three-dimensional (3-D) scaffolds. First we explored the ability of porcine bone marrow precursor cells (MPCs) to differentiate down both the adipogenic and osteogenic pathways within 2-D culture systems, with positive results confirmed by Oil-Red-O and Alizarin Red staining, respectively. Secondly, we examined the influence of heparin on the interaction and behaviour of MPCs when seeded onto PCL-TCP-Col 3-D scaffolds, followed by their induction into the osteogenic lineage. Our 3-D findings suggest that cell metabolism and proliferation increased between days 1 and 14, with deposition of extracellular matrix also observed up to 28 days. However, no noticeable difference could be detected in the extent of osteogenesis for PCL-TCP-Col scaffolds groups with the addition of heparin compared to identical control scaffolds without the addition of heparin.

Heparin regulates colon cancer cell growth through p38 mitogen-activated protein kinase signalling

OBJECTIVES

Heparin acts as an extracellular stimulus capable of activating major cell signalling pathways. Thus, we examined the putative mechanisms utilized by heparin to stimulate HT29, SW1116 and HCT116 colon cancer cell growth.

MATERIALS AND METHODS

Possible participation of the mitogen-activated protein kinase (MAPK) cascade on heparin-induced HT29, SW1116 and HCT116 colon cancer cell growth was evaluated using specific MAPK cascade inhibitors, Western blot analysis, real-time quantitative PCR and FACS apoptosis analysis.

RESULTS

Treatment with a highly specific p38 kinase inhibitor, SB203580, significantly (50-70%) inhibited heparin-induced colon cancer cell growth, demonstrating that p38 MAPK signalling is involved in their heparin-induced proliferative response. This was shown to be correlated with increased (up to 3-fold) phosphorylation of 181/182 threonine/tyrosine residues on p38 MAP kinase. Furthermore, heparin inhibited cyclin-dependent kinase inhibitor p21(WAF1/CIP1) and p53 tumour suppressor gene and protein expression up to 2-fold or 1.8-fold, respectively, and stimulated cyclin D1 expression up to 1.8-fold, in these cell lines through a p38-mediated mechanism. On the other hand, treatment with heparin did not appear to affect HT29, SW1116 and HCT116 cell levels of apoptosis.

CONCLUSIONS

This study demonstrates that an extracellular glycosaminoglycan, heparin, finely modulates expression of genes crucial to cell cycle regulation through specific activation of p38 MAP kinase to stimulate colon cancer cell growth.

Matrix vesicles originate from apical membrane microvilli of mineralizing osteoblast-like Saos-2 cells

In bone, mineralization is tightly regulated by osteoblasts and hypertrophic chondrocytes which release matrix vesicles (MVs) and control extracellular ionic conditions and matrix composition. MVs are the initial sites of hydroxyapatite (HA) mineral formation. Despite growing knowledge about their morphology and function, their biogenesis is not well understood. The purpose of this work was to determine the source of MVs in osteoblast lineage, Saos-2 cells, and to check whether MVs originated from microvilli. Microvilli were isolated from the apical plasma membrane of Saos-2 cells. Their morphology, structure, and function were compared with those of MVs. The role of actin network in MV release was investigated by using microfilament perturbing drugs. When examined by electron microscopy MVs and microvillar vesicles were found to exhibit similar morphology with trilaminar membranes and diameters in the same range. Both types of vesicles were able to induce HA formation. Their electrophoretic profiles displayed analogous enrichment in alkaline phosphatase, Na(+)/K(+) ATPase, and annexins A2 and A6. MVs and microvillar vesicles exhibited almost the same lipid composition with a higher content of cholesterol, sphingomyelin, and phosphatidylserine as compared to plasma membrane. Finally, cytochalasin D, which inhibits actin polymerization, was found to stimulate release of MVs. Our findings were consistent with the hypothesis that MVs originated from cell microvilli and that actin filament disassembly was involved in their biogenesis.

High xylosyltransferase activity in children and during mineralization of osteoblast-like SAOS-2 cells

Skeletal growth and tissue remodelling processes are characterized by an elevated collagen and proteoglycan biosynthesis. The xylosyltransferases I and II are the rate-limiting step enzymes in proteoglycan biosynthesis and serum xylosyltransferase (XT) activity has been shown to be a biomarker for the actual proteoglycan biosynthesis rate. Here, XT, alkaline phosphatase (ALP), bone ALP (BALP) activities were measured in 133 juvenile Caucasians. Serum XT activities in juveniles were elevated and significantly correlated with ALP and BALP. In an osteoblast-like cell model using SAOS-2 cells mineralization and bone nodule formation were induced and XT-I, XT-II and ALP were monitored. Induction of mineralization in SAOS-2 cells resulted in a long-term increase of XT-I mRNA and enzyme activity, which could be paralleled with elevated ALP activity. In addition, HGH and IGF-I treatment of SAOS-2 cells led to an increased expression of XT-I and ALP. These results point to skeletal growth and tissue remodeling as a cause of the high XT activity in children.

Glycosaminoglycan composition changes with MG-63 osteosarcoma osteogenesis in vitro and induces human mesenchymal stem cell aggregation

Osteogenic differentiation is coordinated by the exposure of cells to temporal changes in a combination of growth factors and elements within the extracellular matrix (ECM). Many of the key proteins that drive these changes share the property of being dependent on ECM glycosaminoglycans (GAGs) for their activity. Here, we examined whether GAGs isolated from proliferating, differentiating and mineralizing MG-63 osteosarcoma cells differed in their physical properties, and thus in their capacities to coordinate the osteogenic cascade both in human MG-63 osteosarcoma cells and primary human mesenchymal stem cells (hMSCs). Our results show that the size distribution of GAGs, the expression of GAG-carrying proteoglycan cores and the expression of enzymes involved in their modification systematically change as MG-63 cells mature in culture. When dosed back onto cells exogenously in soluble form, GAGs regulated MG-63 survival and growth in a dose-dependent manner, but not differentiation in either cell type. In contrast, hMSCs aggregated into distinct colonies when grown on GAG-coated substrates, while MG-63 cells did not. Heparin-coated substrates improved hMSC viability without inducing aggregation. These results suggest a complex role for GAGs in coordinating the emergence of the osteoblast phenotype, and provide further evidence for the use of heparans in bone tissue repair applications.

Disruption of cell-matrix interactions by heparin enhances mesenchymal progenitor adipocyte differentiation

Differentiation of marrow-derived mesenchymal progenitors to either the osteoblast or adipocyte lineage is reciprocally regulated. Factors that promote osteoblastogenesis inhibit adipogenesis, while adipogenic factors are inhibitory to osteoblast differentiation. Heparin, a soluble glycosaminoglycan, inhibits bone formation in vivo and osteoblast cell differentiation and function in vitro, and has been shown to promote adipocyte differentiation. To elucidate the role that heparin plays in the adipogenic induction of murine mesenchymal progenitors, we studied immortalized marrow stromal cells (IM-MSC), the MSC cell line, ST2, and 3T3L1 pre-adipocytes. Heparin alone was not sufficient to induce adipogenesis, but enhanced the induction under a variety of adipogenic cocktails. This effect was both dose- and time-dependent. Heparin showed a positive effect at concentrations > 0.1 microg/ml when applied before day 3 during the induction course. Heparin's effect on adipogenesis was independent of cell proliferation, cell density, and extracellular lipid. This effect is likely related to the unique structure of heparin because another polyanionic glycosaminoglycan, dextran sulfate, did not promote adipogenic differentiation. Heparin treatment altered morphology and adhesion characteristics of progenitor cells, resulting in cell rounding and aggregation. As well, heparin counteracted the known inhibitory effect of fibronectin on adipogenesis and decreased basal focal adhesion kinase and paxillin phosphorylation. We conclude that heparin-mediated disruption of cell-matrix adhesion enhances adipogenic potential.

The in vivo assessment of a novel scaffold containing heparan sulfate for tissue engineering with human mesenchymal stem cells

Human mesenchymal stem cells (hMSCs) are an attractive tissue engineering avenue for the repair and regeneration of bone. In this study we detail the in vivo performance of a novel electrospun polycaprolactone scaffold incorporating the glycosaminoglycan heparan sulfate (HS) as a carrier for hMSC. HS is a multifunctional regulator of many key growth factors expressed endogenously during bone wound repair, and we have found it to be a potent stimulator of proliferation in hMSCs. To assess the potential of the scaffolds to support hMSC function in vivo, hMSCs pre-committed to the osteogenic lineage (human osteoprogenitor cells) were seeded onto the scaffolds and implanted subcutaneously into the dorsum of nude rats. After 6 weeks the scaffolds were retrieved and examined by histological methods. Implanted human cells were identified using a human nuclei-specific antibody. The host response to the implants was characterized by ED1 and ED2 antibody staining for monocytes/macrophages and mature tissue macrophages, respectively. It was found that the survival of the implanted human cells was affected by the host response to the implant regardless of the presence of HS, highlighting the importance of controlling the host response to tissue engineering devices.

Heparan Sulfate Proteoglycans (HSPGs) Modulate BMP2 Osteogenic Bioactivity in C2C12 Cells

Cell surface heparan sulfate proteoglycans (HSPGs) have been implicated in bone morphogenetic protein (BMP)-mediated morphogenesis by regulating BMP activity and gradient formation. However, the direct role of HSPGs in BMP signaling is poorly understood. Here we show that HSPGs directly regulate BMP2-mediated transdifferentiation of C2C12 myoblasts into osteoblasts. HSPGs sequester BMP2 at the cell surface and mediate BMP2 internalization. Depletion of cell surface HSPGs by heparinase III treatment or decreased glycosaminoglycan chain sulfation with sodium chlorate enhances BMP2 morpho-genetic bioactivity. The addition of exogenous heparin, a widely used anticoagulant, reduced BMP2 signaling. Our results suggest that cell surface HSPGs mediate BMP2 internalization and modulate BMP2 osteogenic activity.

Cbfa-1 (Runx-2) and osteocalcin expression by human osteoblasts in heparin osteoporosis in vitro

Heparin may cause adverse effects on bone formation following long-term application. The exact pathomechanism is unclear, but in vitro data suggest an impaired osteoblast function. The transcription axis of Cbfa-1 (Runx-2) and osteocalcin is crucial in maintaining an equilibrium of bone formation and resorption in vivo. We used a human osteoblast cell culture model to further investigate the effect of heparin (low-molecular-weight heparin, dalteparin) on the expression of these two regulators of osteoblast differentiation. At high doses, dalteparin caused a significant inhibition of both osteocalcin and Cbfa-1 expression in vitro. Our data support the hypothesis of a direct inhibition of osteoblast function underlying heparin osteoporosis.

The effect of heparin-functionalized PEG hydrogels on three-dimensional human mesenchymal stem cell osteogenic differentiation

Poly(ethylene glycol) (PEG) hydrogels functionalized with heparin were utilized as a three-dimensional culture system for human mesenchymal stem cells (hMSCs). Heparin-functionalized hydrogels supported hMSC viability, as quantified through live/dead imaging, and induced osteogenic differentiation, as measured by increased alkaline phosphatase (ALP) production and osteopontin (OPN) and collagen I (COL I) gene expression over the 5-week study. Further exploration of the potential mechanism of heparin-induced osteogenic differentiation was performed. Specifically, the availability of bone morphogenetic protein 2 (BMP2) and fibronectin (FN) in the culture system was controlled and hMSC osteogenic differentiation was evaluated as a function of the microenvironment. BMP2 availability increased both ALP production and OPN gene expression, while FN increased ALP production, but not OPN gene expression. Furthermore, immunostaining of integrin expression revealed that viability and differentiation were differentially affected by integrin production, where both alpha5beta1 and alphavbeta3 integrin-ligand interactions supported viability, while only the alpha5beta1 integrin played a role in hMSC osteogenic differentiation.

Bone-specific heparan sulfates induce osteoblast growth arrest and downregulation of retinoblastoma protein

The heparan sulfate (HSs) sugars of the extracellular matrix (ECM) play a key role during both development and wound repair in regulating the flow of growth and adhesive factors across their cell surface receptors. The aim of this study was to assess the structural and functional differences of HS chains extracted from the conditioned media (soluble), cell surface, and ECM of primary human osteoblast cultures, and to analyze their effects on osteoblast cell growth. HS chains from these compartments were characterized through a combination of enzymatic degradation, anion exchange chromatography, and molecular sieving. Although the chains were all approximately the same size, they varied systematically in their sulfate content, suggesting differences in their protein-binding domains. When added to pre-confluent hFOB1.19 osteoblast cultures, HS doses exceeding 500 ng/ml inhibited proliferation, without affecting viability, irrespective of their origin. Furthermore, HS doses of 500 ng/ml also downregulated retinoblastoma, Cyclin A and CDK1 protein expression, indicating that high doses of osteoblast HS negatively regulate cell cycle, resulting in growth arrest; when high doses of HS were withdrawn after a prolonged period, linear cell growth was reestablished. Thus, despite differences in sulfation, HS from either the soluble, cell surface, or matrix compartments of primary human osteoblast cultures are functionally similar with respect to their effects on growth. Binding assays revealed that the HS chains bound TGFbeta1, a known inhibitor of osteoprogenitor growth, at higher affinity than a suite of other bone-related, heparin-binding growth factors. Overcoming such sugar-mediated inhibition may prove important for wound repair.

Heparin functionalized PEG gels that modulate protein adsorption for hMSC adhesion and differentiation

Heparin was modified with methacrylate groups, copolymerized with dimethacrylated poly(ethylene glycol), and analyzed as a localized delivery vehicle for bFGF and synthetic extracellular matrix for the differentiation of hMSCs. By deriving cues from molecules normally present in the extracellular matrix (ECM), a complex network of collagens, laminin, fibronectin, glycosaminoglycans, and growth factors, synthetic cell scaffolds can be designed that actively sequester important bioactive signals. Among the glycosaminoglycans, heparin binds reversibly with many proteins, therefore, poly(ethylene glycol) based biomaterials, normally resistant to cell adhesion, functionalized with heparin in order to sequester important proteins, can actively and selectively stimulate desired cell functions. Results demonstrate that methacrylate-modified heparin retained its ability to bind heparin-binding proteins both in solution and when copolymerized with dimethacrylated PEG in a hydrogel. In addition, the heparin functionalized gels can deliver biologically active bFGF for up to 5 weeks. Finally, the gels were examined as a potential scaffold for hMSC culture and were found to promote adhesion, proliferation, and osteogenic differentiation.

Regulated Expression of ADAMTS Family Members in Follicles and Cumulus Oocyte Complexes: Evidence for Specific and Redundant Patterns During Ovulation1

Protease cascades are essential for many biological events, including the LH-induced process of ovulation. ADAMTS1 (a disintegrin and metalloproteinase with thrombospondin-like repeats-1) is expressed and hormonally regulated in the ovary by LH and the progesterone receptor. To determine whether other family members might be expressed and regulated in the rodent ovary, those closely related to ADAMTS1 (ADAMTS4 and ADAMTS5) were analyzed in the mouse ovary by reverse transcription-polymerase chain reaction as well as by Western blot, immunohistochemical, and immunocytochemical analyses using highly specific antibodies. Prior to ovulation, ADAMTS4 and ADAMTS5 were coexpressed in granulosa cells of most follicles, whereas ADAMTS5 was also present in granulosa cells of atretic follicles. Following ovulation, ADAMTS1 and ADAMTS4 (but not ADAMTS5) were expressed in multiple cell types, including those within the highly vascular ovulation cone that marks the site of follicle rupture, endothelial cells of newly forming corpora lutea, and cumulus cells within the ovulated cumulus cell-oocyte complex (COC). Versican, a substrate for ADAMTS1 and ADAMTS4, colocalized with these proteases and hylauronan on the cumulus cell surface. To further characterize induction of these proteases and associated molecules, COCs and granulosa cells were isolated from preovulatory follicles and treated with FSH. In expanded COCs and differentiated granulosa cells, FSH induced expression of ADAMTS4 and versican message and protein, whereas increased levels of ADAMTS1 protein was observed in the media of granulosa cells where it was stabilized by heparin in this in vitro system. These studies provide the first evidence that ADAMTS1, ADAMTS4, and ADAMTS5 are expressed in spatiotemporal patterns that suggest distinct as well as some overlapping functions that relate to the broad expression pattern of versican in granulosa cells of small follicles, expanded COCs, and endothelial cells of the mouse ovary.