The effect of adsorbed serum proteins, RGD and proteoglycan-binding peptides on the adhesion of mesenchymal stem cells to hydroxyapatite

Prior studies from our laboratory have shown that RGD peptides increase the attachment of mesenchymal stem cells (MSCs) to hydroxyapatite (HA), however, RGD does not induce cell spreading when coupled to this type of biomaterial. In an effort to improve MSC spreading, and possibly cell attachment, proteoglycan-binding peptides (KRSR or FHRRIKA) were combined with RGD in the current study. It was found that the peptide combinations did not enhance MSC attachment relative to RGD alone, although a slight amount of spreading was elicited by both KRSR and FHRRIKA. Similar results were obtained with proteoglycan-binding peptides modified with a heptaglutamate domain, a motif that improves peptide tethering to HA. To determine whether differentiation status affected cell responses, MSCs were in vitro differentiated into osteoblasts, and evaluated as before. These experiments revealed that, like MSCs, osteoblasts did not adhere in greater numbers to the peptide combinations. Finally, none of the peptides or peptide combinations were able to stimulate the robust amount of cell adhesion and spreading elicited by serum-coated HA surfaces (of note, five different species of serum were tested). Given the propensity of HA to adsorb proadhesive proteins from blood/serum, we question the utility of functionalizing HA with RGD and/or proteoglycan-binding peptides.     

Regulation of mesenchymal stem cell attachment and spreading on hydroxyapatite by RGD peptides and adsorbed serum proteins

The successful development of biomaterials must take into consideration how those surfaces will interact with in vivo processes such as adsorption of endogenous proteins. In this study, we examined whether modifying highly adsorbent materials like hydroxyapatite (HA) with RGD peptides would improve mesenchymal stem cell (MSC) adhesion. We found that RGD, alone, was not sufficient to promote full cell spreading. However, given that RGD-modified HA will likely adsorb osteogenic serum proteins in vivo, we evaluated MSC behavior on HA pre-coated with RGD, then over-coated with serum (RGD/FBS). Interestingly, RGD/FBS coatings additively stimulated MSC attachment and spreading compared to either coating alone, but only at low RGD coating concentrations. High RGD concentrations inhibited cell attachment, and completely eliminated cell spreading on RGD/FBS surfaces. To better understand the mechanism by which RGD and adsorbed serum proteins interactively regulate cell behavior, we monitored the deposition of fibronectin (FN) from serum onto HA pre-coated with increasing RGD concentrations. These studies showed that high RGD concentrations did not inhibit FN adsorption, therefore cell spreading is attenuated by mechanisms other than lack of FN availability. Collectively, our results suggest a potential therapeutic benefit for functionalizing HA with RGD, however such a benefit will likely depend upon the RGD density.     

The effect of RGD peptides on osseointegration of hydroxyapatite biomaterials

Given that hydroxyapatite (HA) biomaterials are highly efficient at adsorbing proadhesive proteins, we questioned whether functionalizing HA with RGD peptides would have any benefit. In this study, we implanted uncoated or RGD-coated HA disks into rat tibiae for 30 min to allow endogenous protein adsorption, and then evaluated mesenchymal stem cell (MSC) interactions with the retrieved disks. These experiments revealed that RGD, when presented in combination with adsorbed tibial proteins (including fibronectin, vitronectin and fibrinogen), has a markedly detrimental effect on MSC adhesion and survival. Moreover, analyses of HA disks implanted for 5 days showed that RGD significantly inhibits total bone formation as well as the amount of new bone directly contacting the implant perimeter. Thus, RGD, which is widely believed to promote cell/biomaterial interactions, has a negative effect on HA implant performance. Collectively these results suggest that, for biomaterials that are highly interactive with the tissue microenvironment, the ultimate effects of RGD will depend upon how signaling from this peptide integrates with endogenous processes such as protein adsorption.     

NCO-sP(EO-stat-PO) surface coatings preserve biochemical properties of RGD peptides

We have previously reported that star shaped poly(ethylene oxide-stat-propylene oxide) macromers with 80% EO content and isocyanate functional groups at the distal ends [NCO-sP(EO-stat-PO)] can be used to generate coatings that are non-adhesive but easily functionalized for specific cell adhesion. In the present study, we investigated whether the NCO-sP(EO-stat-PO) surfaces maintain peptide configuration-specific cell-surface interactions or if differences between dissimilar binding molecules are concealed by the coating. To this end, we have covalently immobilized both linear-RGD peptides (gRGDsc) and cyclic-RGD (RGDfK) peptides in such coatings. Subsequently, SaOS-2 or human multipotent mesenchymal stromal cells (MSC) were seeded on these substrates. Cell adhesion, spreading and survival was observed for up to 30 days. The time span for cell adherence was not different on linear and cyclic RGD peptides, but was shorter in comparison to the unmodified glass surface. MSC proliferation on cyclic RGDfK modified coatings was 4 times higher than on films functionalized by linear gRGDsc sequences, underlining that the NCO-sP(EO-stat-PO) film preserves the configuration-specific biochemical peptide properties. Under basal conditions, MSC expressed osteogenic marker genes after 14 days on cyclic RGD peptides, but not on linear RGD peptides or the unmodified glass surfaces. Our results indicate specific effects of these adhesion peptides on MSC biology and show that this coating system is useful for selective testing of cellular interactions with adhesive ligands.     

The effect of collagen I mimetic peptides on mesenchymal stem cell adhesion and differentiation,and on bone formation at hydroxyapatite surfaces

Integrin-binding peptides increase cell adhesion to naive hydroxyapatite (HA), however, in the body, HA becomes rapidly modified by protein adsorption. Previously we reported that, when combined with an adsorbed protein layer, RGD peptides interfered with cell adhesion to HA. In the current study we evaluated mesenchymal stem cell (MSC) interactions with HA disks coated with the collagen-mimetic peptides, DGEA, P15 and GFOGER. MSCs adhered equally well to disks coated with DGEA, P15, or collagen I, and all three substrates, but not GFOGER, supported greater cell adhesion than uncoated HA. When peptide-coated disks were overcoated with proteins from serum or the tibial microenvironment, collagen mimetics did not inhibit MSC adhesion, as was observed with RGD, however neither did they enhance adhesion. Given that activation of collagen-selective integrins stimulates osteoblastic differentiation, we monitored osteocalcin secretion and alkaline phosphatase activity from MSCs adherent to DGEA or P15-coated disks. Both of these osteoblastic markers were upregulated by DGEA and P15, in the presence and absence of differentiation-inducing media. Finally, bone formation on HA tibial implants was increased by the collagen mimetics. Collectively these results suggest that collagen-mimetic peptides improve osseointegration of HA, most probably by stimulating osteoblastic differentiation, rather than adhesion, of MSCs.     

Collagen-infiltrated porous hydroxyapatite coating and its osteogenic properties: in vitro and in vivo study

Bone-implant interface is critical for the early fixation of orthopedic implants. In this study, porous hydroxyapatite (HA) coatings were prepared through a liquid precursor plasma spraying process and were infiltrated with the collagen, alone and with the additional incorporation of recombinant human bone morphogenetic protein-2 (rhBMP-2) and RGD peptide (RGD). The results showed significantly improved mesenchymal stem cell (MSC) adhesion, proliferation, and differentiation on collagen-modified HA coatings, partially benefited from the formation of a fibrous network due to the self-reconstitution of collagen on the HA surface. Further enhancements on MSC proliferation and differentiation were generally observed through the additional incorporation of bone morphogenetic protein (BMP) and RGD. The osteoinductive and osteoconductive properties of the collagen/BMP-modified HA coatings were studied in vivo. Clear ectopic bone formation and significantly accelerated bone growth rate (29% increase, p < 0.05) have been observed after 1-month implantation of HA-collagen/rhBMP-2-coated Ti alloy samples into the rabbit muscle and dog femora, respectively. Overall, our results suggest that collagen-modified HA coating surface is a far superior substrate for cell attachment, proliferation, and differentiation, and collagen can be used an efficient carrier for BMP in vivo. Therefore, modification of HA coating with collagen is a simple but effective biomimetic approach to enhancing the osteointegration and early fixation of bone-implant interface.     

Enhancement of peptide coupling to hydroxyapatite and implant osseointegration through collagen mimetic peptide modified with a polyglutamate domain

Hydroxyapatite (HA) is a widely-used biomaterial for bone repair due to its high degree of osteoconductivity. However, strategies for improving HA performance by functionalizing surfaces with bioactive factors are limited. In this study, we explored the use of a HA-binding domain (heptaglutamate, "E7") to facilitate coupling of the collagen mimetic peptide, DGEA, to two types of HA-containing materials, solid HA disks and electrospun polycaprolactone matrices incorporating nanoparticulate HA. We found that the E7 domain directed significantly more peptide to the surface of HA and enhanced peptide retention on both materials in vitro. Moreover, E7-modified peptides were retained in vivo for at least two months, highlighting the potential of this mechanism as a sustained delivery system for bioactive peptides. Most importantly, E7-DGEA-coupled HA, as compared with DGEA-HA, enhanced the adhesion and osteoblastic differentiation of mesenchymal stem cells, and also increased new bone formation and direct bone-implant contact on HA disks implanted into rat tibiae. Collectively, these results support the use of E7-DGEA peptides to promote osteogenesis on HA substrates, and further suggest that the E7 domain can serve as a universal tool for anchoring a wide variety of bone regenerative molecules to any type of HA-containing material.     

Additive effect of RGD coating to functionalized titanium surfaces on human osteoprogenitor cell adhesion and spreading

Titanium-based biomaterials for endosseous implants have found widespread applications in the orthopedic, maxillofacial, and dental domains. Indeed, the surface characteristics such as their chemical modification control considerably the cellular response and, subsequently, the quality and the quantity of new-formed bone around the implant. In this study, human osteoprogenitor (HOP) cell adhesion on different titanium surfaces functionalized with hydroxyapatite (HA), type I collagen, or Arg-Gly-Asp (RGD)-containing peptides is investigated by the quartz crystal resonators and by confocal laser scanning microscopy (CLSM) for the imaging of focal contact formation. Data obtained by quartz crystal resonator technique revealed that RGD-containing peptides alone increase HOP cell adhesion in early time period of culture. Moreover, association of RGD-containing peptides with either type I collagen or with HA layers induces an additive effect on HOP cell adhesion compared to Ti-Coll or Ti-HA. CLSM shows both the area of focal contact by cell unit and the cytoskeleton network organization to differ according to the surfaces. Interestingly, association of RGD-containing peptides with HA layers induces an additive effect on focal contact formation on HOP cells compared to Ti-HA alone. These data confirm that an RGD peptide effect occurs in the early time of culture, which is beneficial for osteoblast to spreading, differentiation, and survival.     

RGD多肽修饰的改性PLGA仿生支架材料对骨髓间充质干细胞粘附、增殖及分化影响的研究

目的：探索RGD多肽修饰的改性PLGA支架材料上骨髓基质细胞的增殖、粘附及分化情况。方法用异型双功能交联剂Sulfo-LC-SPDP将GRGDSPC多肽共价结合到改性PLGA支架材料上，以未接多肽的改性PLGA材料做对照，取第三代MSC接种到材料上，培养1d、2d、3d、4d后比较材料上的细胞密度来反映细胞的增殖程度；取第三代MSC接种到材料上，培养4h、12h后沉淀法定量检测粘附的细胞数，培养24h后摄光镜图像比较粘附细胞的数量和形态，并用FITC连接的鬼笔环肽对细胞骨架染色，在荧光显微镜下观察细胞骨架的组织情况；取第三代MSC接种到材料上，用成骨性培养基培养7d、14d、21d，检测细胞中ALP活性来了解MSC分化情况。结果：培养1d、2d、3d、4d后细胞的增殖程度无显著性差异；培养4h、12h后实验组细胞粘附率均显著高于对照组，且24h后细胞的粘附质量、细胞骨架的组织情况也较对照组为好；培养14d后实验组细胞表达显著高的ALP活性。结论：RGD多肽修饰对细胞增殖无明显促进作用，但能提高改性PLGA支架材料对骨髓基质细胞的粘附性，对MSC向成骨细胞分化有显著促进作用。     

Using hydroxyapatite nanoparticles and decreased crystallinity to promote osteoblast adhesion similar to functionalizing with RGD

Better materials are needed to promote bone growth. For this reason, the present study created nanometer crystalline hydroxyapatite (HA) and amorphous calcium phosphate compacts functionalized with the arginine-glycine-aspartic acid (RGD) peptide sequence. Crystalline HA and amorphous calcium phosphate nanoparticles were synthesized by a wet chemical process followed by a hydrothermal treatment for 2 h at 200 degrees C and 70 degrees C, respectively. Resulting particles were then pressed into compacts. For the preparation of conventional HA particles (or those with micron diameters), the aforementioned pressed compacts were sintered at 1,100 degrees C for 2 h. Peptide functionalization was conducted by means of a three step reaction procedure: silanization with 3-aminopropyltriethoxysilane (APTES), cross-linking with N-succinimidyl-3-maleimido propionate (SMP), and finally peptide immobilization. The three step reaction procedure was characterized by a novel 3-(4-carboxybenzoyl)quinoline-2-carboxaldehyde (CBQCA) fluorescence technique. For all materials, results showed that the immobilization of the cell adhesive RGD sequence increased osteoblast (bone-forming cell) adhesion compared to those non-functionalized and those functionalized with the noncell adhesive control peptide (RGE) after 4 h. However, surprisingly, results also showed that the adhesion of osteoblasts on non-functionalized amorphous nanoparticulate calcium phosphate was similar to conventional HA functionalized with RGD. Osteoblast adhesion on nanocrystalline HA (unfunctionalized and functionalized with RGD) was below that of the respective functionalized amorphous calcium phosphate but above that of the respective functionalized conventional HA. In this manner, results of this study suggest that decreasing the particulate size into the nanometer regime and reducing crystallinity of calcium phosphate based materials may promote osteoblast adhesion to the same degree as the well-established techniques of functionalizing conventional HA with RGD.     

Attachment of hyaluronan to metallic surfaces

Metal implants are in general not compatible with the tissues of the human body, and in particular, blood exhibits a severe hemostatic response. Herein we present results of a technique to mask the surface of metals with a natural biopolymer, hyaluronan (HA). HA has minimal adverse interactions with blood and other tissues, but attachment of bioactive peptides can promote specific biological interactions. In this study, stainless steel was cleaned and then surface-modified by covalent attachment of an epoxy silane. The epoxy was subsequently converted to an aldehyde functional group and reacted with hyaluronan through an adipic dihydrazide linkage, thus covalently immobilizing the HA onto the steel surface. Fluorescent labeling of the HA showed that the surface had a fairly uniform covering of HA. When human platelet rich plasma was placed on the HA-coated surface, there was no observable adhesion of platelets. HA derivatized with a peptide containing the RGD peptide sequence was also bound to the stainless steel. The RGD-containing peptide was bioactive as exemplified by the attachment and spreading of platelets on this surface. Furthermore, when the RGD peptide was replaced with the nonsense RDG sequence, minimal adhesion of platelets was observed. This type of controlled biological activity on a metal surface has potential for modulating cell growth and cellular interactions with metallic implants, such as vascular stents, orthopedic implants, heart valve cages, and more.     

Photopolymerized hyaluronic acid-based hydrogels and interpenetrating networks

Hyaluronic acid (HA) was derivatized with methacrylic esters used for the preparation of hydrogels via photopolymerization. Poly(ethylene glycol) diacrylate (PEG-DA) with a molecular weight of 570 was also used as a comacromonomer to improve elastic modulus and swelling behavior. The hydrogels were readily degraded by hyaluronidase and their mechanical properties could be modulated by HA molecular weight and concentration of PEG-DA. The incorporation of RGD peptides allowed modulation of the HA properties from cell non-adhesive to adhesive. Human dermal fibroblasts were cultured on the RGD, RDG, and non-functionalized HA hydrogels for up to 7d, showing adhesion and proliferation only with incorporated RGD.     

RGD modified polymers: biomaterials for stimulated cell adhesion and beyond

Since RGD peptides (R: arginine; G: glycine; D: aspartic acid) have been found to promote cell adhesion in 1984 (Cell attachment activity of fibronectin can be duplicated by small synthetic fragments of the molecule, Nature 309 (1984) 30), numerous materials have been RGD functionalized for academic studies or medical applications. This review gives an overview of RGD modified polymers, that have been used for cell adhesion, and provides information about technical aspects of RGD immobilization on polymers. The impacts of RGD peptide surface density, spatial arrangement as well as integrin affinity and selectivity on cell responses like adhesion and migration are discussed.     

Surface modification for controlled studies of cell-ligand interactions

This work describes a method for coupling cell adhesion peptides to hydrophobic materials for the purpose of controlling surface peptide density while simultaneously preventing nonspecific protein adsorption. PEO/PPO/PEO triblock copolymers (Pluronic F108) were equipped with terminal pyridyl disulfide functionalities and used to tether RGD containing peptides to polystyrene (PS). The density of F108 on PS was 1.4 E5 +/- 2.12 E1 molecules/microm2. XPS and ToF SIMS indicated that the F108 coating was homogeneous and that the unmodified and activated F108 distributed evenly on PS. By mixing unmodified F108 with PDS-activated F108 prior to adsorption, it was possible to vary peptide density between 0 and 8.7 E4 +/- 2.66 E3 peptides/microm2, while otherwise, maintaining consistent surface properties. GRGDSY grafted PS supported cell attachment, spreading, and development of cytoskeletal structure, all of which were found to increase with increasing peptide density. Cell proliferation followed this same trend, however, maximal growth occurred at a submaximal peptide density. Cell aspect ratio varied in a biphasic manner with GRGDSY density. F108 coated PS and GRGESY grafted PS were inert to cell adhesion. Cells released from GRGDSY grafted PS upon addition of either a reducing agent or free GRGDSY, which indicates that cell-substrate interactions were mediated solely by the tethered peptides.     

Diverse mechanisms of osteoblast spreading on hydroxyapatite and titanium

Hydroxyapatite (HA) is an osteoconductive implant material. We previously demonstrated that RGD peptides regulate the spreading of HOS cells on HA but not on titanium, speculating that the osteoconductivity of HA might be attributed to this RGD domain-dependent spreading of osteoblasts. To confirm this hypothesis, the molecules which regulate the spreading of HOS cells on HA and on titanium were investigated. The 50% effective dose (ED50) of RGD peptide for the spreading on HA was five fold lower comparing to titanium. Anti-alphaV integrin antibody, vitronectin, and fibronectin inhibited the spreading on HA but not on titanium. In Western blot analysis, vitronectin and fibronectin were found in components adsorbed to HA but not to titanium. Taken together, the spreading of HOS cells on HA but not on titanium requires the interaction of alphaV integrin and its ligands. The ED50 of the RGD peptides on titanium but not on HA was remarkably reduced by neuraminidase treatment, that by itself could not inhibit the spreading on both materials. This phenomenon suggests that RGD domain and sialic acid cooperatively but not independently mediate the spreading of HOS cells on titanium. Collectively, the molecules regulating the spreading on HA are apparently different from those on titanium. The spreading of osteoblasts mediated by RGD domain of vitronectin and fibronectin might contribute to the osteoconductive ability of HA.     

Cellular recognition of synthetic peptide amphiphiles in self-assembled monolayer films

The incorporation of lipidated cell adhesion peptides into self-assembled structures such as films provides the opportunity to develop unique biomimetic materials with well-organized interfaces. Synthetic dialkyl tails have been linked to the amino-terminus, carboxyl-terminus, and both termini of the cell recognition sequence Arg-Gly-Asp (RGD) to produce amino-coupled, carboxyl-coupled, and looped RGD peptide amphiphiles. All three amphiphilic RGD versions self-assembled into fairly stable mixed monolayers that deposited well as Langmuir-Blodgett films on surfaces, except for films containing amino-coupled RGD amphiphiles at high peptide concentrations. FT-IR studies showed that amino-coupled RGD head groups formed the strongest lateral hydrogen bonds. Melanoma cells spread on looped RGD amphiphiles in a concentration-dependent manner, spread indiscriminately on carboxyl-coupled RGD amphiphiles, and did not spread on amino-coupled RGD amphiphiles. Looped RGD amphiphiles promoted the adhesion, spreading, and cytoskeletal reorganization of melanoma and endothelial cells while control looped Arg-Gly-Glu (RGE) amphiphiles inhibited them. Antibody inhibition of the integrin receptor alpha3beta1 blocked melanoma cell adhesion to looped RGD amphiphiles. These results confirm that novel biomolecular materials containing synthetic peptide amphiphiles have the potential to control cellular behavior in a specific manner.     

Platelet and endothelial adhesion on fluorosurfactant polymers designed for vascular graft modification

A prominent failure mechanism of small diameter expanded polytetrafluoroethylene (ePTFE) vascular grafts is platelet-mediated thrombosis. We have designed a surface modification for ePTFE consisting of a self-assembling fluorosurfactant polymer (FSP) bearing biologically active ligands, including adhesive peptides and polysaccharide moieties. The goal of this biomimetic construct is to improve graft hemocompatibility by promoting rapid surface endothelialization, whereas minimizing platelet adhesion. Here we present a direct comparison of platelet and endothelial cell (EC) adhesion to FSPs containing one of three cell-adhesion peptides: cyclic Arg-Gly-Asp-D-Phe-Glu (cRGD), cyclic *Cys-Arg-Arg-Glu-Thr-Ala-Trp-Ala-Cys* (cRRE, *denotes disulfide bond cyclization), linear Gly-Arg-Gly-Asp-Ser-Pro-Ala (RGD), or a polysaccharide moiety: oligomaltose (M-7), later designed to prevent nonspecific protein adhesion. Measurements of soluble peptide-integrin binding indicated that cRRE exhibits very low affinity for the alpha(IIb)beta(3) platelet fibrinogen receptor. Static and dynamic adhesion of washed, activated platelets on FSP-modified surfaces revealed that M-7 and cRRE promote significantly less platelet adhesion compared to RGD and cRGD FSPs, whereas EC adhesion was similar on all peptide FSPs and minimal on M-7 FSP. These results illustrate the potential for ligands presented in a FSP surface modification to selectively adhere ECs with limited platelet attachment.     

Conception, élaboration et caractérisation de matériaux bioactifs

One promising strategy to control the interactions between biomaterial surfaces and attaching cells involves grafting of adhesion peptides as RGD peptides (R: arginine; G: glycine; D: aspartic acid) to materials on which protein adsorption, which mediates unspecific cell adhesion, is essentially suppressed. This review gives an overview of RGD modified materials, that have been used for cell adhesion, and provides information about technical aspects of RGD immobilization on materials. The impacts of RGD peptide surface density, spatial arrangement as well as integrin affinity and selectivity on cell responses like adhesion and migration are discussed. We have tried to relate one of numerous scientifics adventures initiated by Charles Baquey within our laboratory. This review is dedicated to him for his enthusiasm in the development of project and for his wish of always leading of a professional blooming of his students.     

Cellular and transcriptomic analysis of human mesenchymal stem cell response to plasma-activated hydroxyapatite coating

Atmospheric pressure plasma has recently emerged as a technique with a promising future in the medical field. In this work we used the technique as a post-deposition modification process as a means to activate hydroxyapatite (HA) coatings. Contact angle goniometry, optical profilometry, scanning electron microscopy morphology imaging and X-ray photoelectron spectroscopy analysis demonstrate that surface wettability is improved after treatment, without inducing any concomitant damage to the coating. The protein adsorption pattern has been found to be preferable for MSC, and this may result in greater cell attachment and adhesion to plasma-activated HA than to untreated samples. Cell cycle distribution analysis using flow cytometry reveals a faster transition from G(1) to S phase, thus leading to a faster cell proliferation rate on plasma-activated HA. This indicates that the improvement in surface wettability independently enhances cell attachment and cell proliferation, which is possibly mediated by FAK phosphorylation. Pathway-specific polymerase chain reaction arrays revealed that wettability has a substantial influence on gene expression during osteogenic differentiation of human MSC. Plasma-activated HA tends to enhance this process by systemically deregulating multiple genes. In addition, the majority of these deregulated genes had been appropriately translated, as confirmed by ELISA protein quantification. Lastly, alizarin red staining showed that plasma-activated HA is capable of improving mineralization for up to 3 weeks of in vitro culture. It was concluded from this study that atmospheric pressure plasma is a potent tool for modifying the biological function of a material without causing thermal damage, such that adhesion molecules and drugs might be deposited on the original coating to improve performance.     

表面修饰对羟基磷灰石细胞相容性的影响

探讨精氨酸-甘氨酸-天冬氨酸(Arg-Gly-Asp,RGD)多肽表面修饰对羟基磷灰石(hydroxyapatite,HA)细胞相容性的影响。以骨髓基质干细胞(marrow stromal stem cells,MSCs)复合精氨酸-甘氨酸-天冬氨酸多肽表面修饰的羟基磷灰石或单纯材料培养制备组织工程骨,观察骨髓基质干细胞的粘附和生长情况,检测细胞活力和碱性磷酸酶(alkaline phosphatase,ALP)活性,流式细胞仪分析细胞周期。结果表明:骨髓基质干细胞在材料表面和孔隙内均可粘附和生长,粘附于RGD多肽修饰羟基磷灰石的细胞活力和碱性磷酸酶活性明显高于未经RGD多肽修饰组(P<0.01,P<0.05)。各组细胞周期未见明显变化,未见异倍体细胞。说明RGD多肽表面修饰对HA材料的细胞相容性有明显的优化作用。