Abstract:
Oligonucleotides having the ability to stimulate osteogenesis in vertebrate animals, including humans, are disclosed. These osteogenic oligonucleotides can be used in a wide range of clinical procedures to replace and restore osseous and periodontal defects or to facilitate the successful implantation of prosthesis and distraction procedures in bones. Methods for generation of bone in an area of an animal where skeletal tissue is deficient are provided. They consist in the local or systematic administration of a composition comprising one or more of the osteogenic oligonucleotides to the animal, in a pharmaceutically acceptable carrier. The composition is administered in an amount effective to induce osteogenesis at the bone site.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to the use of both osteogenic oligonucleotides and pharmaceutical compositions to induce bone growth in vivo. More in details it refers to oligonucleotides having about 14 to 100 nucleotides that have the ability to stimulate the osteogenesis in animals, including human. 
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       BACKGROUND OF THE INVENTION 
       [0098]    Bone is a complex, highly organized, connective tissue that is continuously remodelled during the life of an adult by cellular events that initially break it down (osteoclastic resorption) and then rebuild it (osteoblastic formation). This remodelling process occurs in discrete sites throughout the skeleton. Bone is the only organ capable of complete repair without the intervention of a fibrous scar (Hult. A. 1989. Current concepts of fracture healing. Clin. Orthop. Relat. Res. 249:265-384.). However, there are clinical situations that require enhancement of the healing to ensure the rapid restoration of bone function, such as orthopaedic and maxillofacial surgery. On the other hand, some events, including aging, poor blood supply, and diabetes, may lead to prevent fracture healing (J. A. Buckwalter, T. A. Einhorn, M. E. Bolander and R. L. Cruess, Healing of the musculoskeletal tissues. In: C. A. Rockwood, D. P. Green, R. W. Bucholz and J. D. Heckman, Editors, Fracture in Adults, Lippincott-Raven, New York (1996), pp. 261-304.). The restoration of an osteoporotic fracture is also delayed since the mechanical strength of the fracture site is decreased due to an insufficient amount of callus and calcification (L. J. Melton, III, Epidemiology of fractures. In: B. L. Riggs and L. J. Melton, III, Editors, Osteoporosis: Etiology, Diagnosis, and Management, Lippincott-Raven, Philadelphia (1995), pp. 225-247; W. R. Walsh, P. Sherman, C. R. Howlett, D. H. Sonnabend and M. G. Ehrlich, Fracture healing in a rat osteopenia model. Clin. Orthop. Relat. Res. 342 (1997), pp. 213-227.). Thus, the development of agents to enhance osteogenesis would be a significant pharmacological advancement in terms of accelerating both fracture healing and the surgical procedures involving bone repair and of preventing fractures in patients suffering osteogenic dysfunctions. 
         [0099]    A number of growth factors and cytokines are present in high levels at fracture sites and many of these proteins play important roles in promoting bone repair (M. E. Bolander, Regulation of fracture repairs by growth factors. Proc. Soc. Exp. Biol. Med. 200 (1992), pp. 165-170.). Drug therapies using various growth factors such as bone morphogenetic proteins (BMPs), transforming growth factor β (TGF-β), insulin-like growth factors (IGFs), fibroblast growth factors (FGFs), and platelet-derived growth factor (PDGF) may be useful since local application of these molecules has been shown to induce bone regeneration in animal models (Lind M (1996) Growth factors: Possible new clinical tools. Acta Orthop. Scand. 67: 407-417). 
         [0100]    These findings indicate that the clinical use of these growth factors may become possible new therapies for enhancing fracture healing. However, the safety and cost-effectiveness of these growth factors must be considered. Therefore, there has been substantial interest in developing chemical compounds that safely promote bone formation and facilitate fracture repair. One example of such a compound is the TAK-778, a derivative of the ipriflavone (7-isopropoxy-isoflavone) which has osteogenic activity “in vitro” and “in vivo” (: Notoya K, Nagai H, Oda T, Gotoh M, Hoshino T, Muranishi H, Taketomi S, Sohda T, Makino H (1999). Enhancement of osteogenesis in vitro and in vivo by a novel osteoblast differentiation promoting compound, TAK-778. J Pharmacol Exp Ther. 290:1054-64). Utility of this compound for human use must be proved in clinical trials. 
         [0101]    We now disclose that oligonucleotides having about 14 to 100 nucleotides are compounds with potent osteogenic activity. 
         [0102]    It is an object of the present invention to provide one or more of the osteogenic oligonucleotides of this invention to an animal with a skeletal (bony) tissue deficiency to produce mature, morphologically normal bone where it is needed. This object will become apparent to those skilled in the art. 
       SUMMARY OF THE INVENTION 
       [0103]    The above object is achieved by providing a method for bone generation at a site of an animal where skeletal tissue is deficient and which consists in the administration of an effective amount of a composition comprising one or more of the osteogenic oligonucleotides of this invention to the animal, locally at the site or systemically as needed in each case, in a pharmaceutically acceptable carrier, the composition being administered in an amount effective to induce bone growth at the site. 
         [0104]    This aspect of the invention enables the generation of normal mature bone in the skeleton in general or locally as required. Pre-clinical results using as example some of the osteogenic ODNs of this invention described below show new bone formation in bone defects in rats, and new bone formation in bone defects in primates. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0105]      FIG. 1  shows an X-ray radiographic analysis of the tibias of a rat, at osteotomy sites, 7, 21 and 35 days after operation, both in the placebo (A, B and C) and in IMT504-treated (D, E and F) bone. 
           [0106]      FIG. 2  shows photographs of the tibias of a rat, at osteotomy sites, 35 days after operation both in the placebo (A) and in IMT504-treated (B) bone. 
           [0107]      FIG. 3  shows microphotographs of the tibias of a rat, at osteotomy sites, 35 days after operation both in the placebo (A) and in IMT504-treated (B) bone. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0108]    “Inducing bone growth” means promoting the formation of morphologically normal, mature bone only at a site where there is a bone deficiency that needs to be replaced. Mature bone is bone of any type, whether cortical or trabecular, that is mineralized as opposed to immature or cartilaginous bone as would be formed in a neonatal model. Morphologically normal bone is bone that is histologically detected as normal (i.e., consisting of endochondral or membranous type lamellar bone and including marrow spaces with osteoblasts and osteoclasts). This is in contrast, for example, to callous formation with a fibrotic matrix as seen in the first stage of fracture healing. Thus, the bone induction herein is contemplated not only as acceleration of bone regeneration, as in a fracture, but also as stimulation of the formation of bone that is returned to its normal morphological state. “Skeletal tissue deficiency” refers to a deficiency in bone at any site, originated as a result of either surgical intervention or fracture, and where bone it is desired to restore the bone. 
         [0109]    By “osteogenesis” is meant the process by which bone develops. 
         [0110]    By “osteogenic” cells is meant cells able to proliferate and to differentiate into osteoblasts and osteocytes. 
         [0111]    By “osteoblasts” is meant mature bone cell concerned with synthesis and secretion of bone extracellular organic constituents. 
         [0112]    By “osteocytes” is meant cells that are essentially osteoblasts surrounded by the products they secrete. 
         [0113]    By “animal” is meant any animal having a vertebrate structure, preferably a mammal, and most preferably a human. 
         [0114]    A “subject” refers to an animal of the order primate, including humans. 
         [0115]    As used herein, the term “oligonucleotide” or “oligo” shall mean multiple nucleotides (i.e. molecules comprising a sugar, e.g. ribose or deoxyribose, linked to a phosphate group and to an exchangeable organic base, which is either a substituted pyrimidine (e.g. cytosine (C), thymine (T) or uracil (U)) or a substituted purine (e.g. adenine (A) or guanine (G)). The term “oligonucleotide” as used herein refers to both oligoribonucleotides (ORNs) and oligodeoxyribonucleotides (ODNs). The term “oligonucleotide” shall also include oligonucleosides (i.e. an oligonucleotide minus the phosphate) and any other organic base containing polymer. Oligonucleotides can be obtained from existing nucleic acid sources (e.g. genomic or cDNA), but are preferably synthetic (e.g. produced by oligonucleotide synthesis). 
         [0116]    An “oligonucleotide” refers to multiple nucleotides linked by phosphodiester bonds. 
         [0117]    An “immunostimulatory oligonucleotide” refers to an oligonucleotide which stimulates (i.e. has a mitogenic effect on, induces, increases or decreases cytokine expression by) a cell of the immune system (i.e. a lymphocyte or a macrophage) in a statistically significant manner. 
         [0118]    A “CpG” refers to a cytosine-guanine dinucleotide. 
         [0119]    A “CpG oligonucleotide” refers to an oligonucleotide which stimulates a cell of the immune system, and whose immunostimulatory activity critically depends on the presence of at least one CpG in its sequence. 
         [0120]    A “non-CpG oligonucleotide” refers to an oligonucleotide that stimulates a cell of the immune system, and whose immunostimulatory activity does not critically depend on the presence of a CpG in its sequence. 
       MODES FOR CARRYING OUT THE INVENTION 
       [0121]    The invention is carried out in one aspect by mixing one or more of the osteogenic oligonucleotides of this invention with a suitable pharmaceutical carrier and by administering the resulting composition locally or systemically as required to an animal in order to induce formation of normal, adult bone in bone lesions. Osteogenic cells and their precursor cells should be present at the lesion site or sites. If the lesion site or sites does not naturally have a source of osteogenic cells present, the pharmaceutical composition may also contain an osteogenic cell source, in an amount sufficient to induce bone growth. 
         [0122]    Examples of indications where promotion of bone repair at a skeletal site or sites is important include: periodontal disease where root socket healing is impaired (tooth socket sites), non-union fractures (including primary treatment of high risk fractures and adjunctive treatment with bone grafting or bone substitutes for established non-union fractures), large bony defects caused by trauma or surgery [e.g., partial mandibular resection for cancer, large cranial defects, spinal (vertebral) fusions, correction of severe scoliosis by surgical alignment held in place with a Harrington bar (to shorten the six-month period normally required for a body cast), and spinal fractures with open reduction (to decrease significantly the period of immobilization)], and rapid stabilization and enhanced fixation of artificial prostheses and spacer bars, oral joints, and bone replacements. 
         [0123]    Examples of the latter include plastic and reconstructive surgery, fixation of permanent dentures into mandible, enhanced fixation of accepted Joint prosthesis, e.g., hips, knees, and shoulders (leading to the acceptance of prostheses that are unacceptable due to rapid loosening and instability), and limb salvage procedures, usually associated with malignancy (the bone shaft may be removed but the articular surfaces are left in place and connected by a space bar; rapid and enhanced fixation is required for success). If the site constitutes a periodontal site, i.e., one that involves the teeth, gums, and dental sockets, the osteogenic oligonucleotides of this invention could be administered in conjunction with an exogenously added source of osteogenic cells. 
         [0124]    In one preferred embodiment, the osteogenic oligonucleotides of this invention are administered by coating a device with the composition containing one or more of the oligonucleotides of this invention and by implanting the device into the animal at the site of the deficiency. The composition may also contain an osteogenic cell source when the site is deficient in such cells. The device may consist in any device suitable for implantation, including a molded implant, plug, prosthetic device, capsule, titanium alloy, sponge, or ceramic block. Examples of suitable delivery vehicles useful as devices are those disclosed by Nade et al., Clin. Orthop. Rel. Res., 181: 255-263 (1982); Uchida et al., J. Biomed. Mat. Res., 21: 1-10 (1987); Friedenstein et al., Exp. Hematol., 10: 217-227 (1982); Deporter et al., Calcif. Tissue Int., 42: 321-325 (1988); McDavid et al., J. Dent. Res., 58: 478-483 (1979); Ohgushi et al., J. Orthopaedic Res., 7: 568-578 (1989), Aprahamian et al., J. Biomed. Mat. Res., 21: 965-977 (1986) and Emmanual et al., Stain. Tech., 62: 401-409 (1987). 
         [0125]    For bone defects involving gaps, such as a dry socket or a non-union fracture, a plug may be used to fill the gap. The plug may be composed of, for example, hydroxyapatite or collagen on which the composition containing one or more of the oligonucleotides of this invention adsorbed. For larger bone defects resulting from, e.g., trauma or skeletal reconstruction around an ulcer or hip prosthesis, the device is preferably a made-to-fit ceramic block. More preferably, the ceramic block comprises 0-100% hydroxyapatite and the remaining 100-0% tricalcium phosphate, by weight, most preferably 60% hydroxyapatite and 40% tricalcium phosphate. 
         [0126]    In a specific embodiment for a jaw implant, a calcium carbonate moldable material or Interpore™ molding device is molded to fit the jaw, using a 3-dimensional x-ray of the jaw before surgery. The molded material is impregnated with the composition containing one or more of the oligonucleotides of this invention. Then, dispensed bone marrow from another site of the animal (e.g., from the hip) is infiltrated into the mold, and the mold is placed into the jaw for final implantation. 
         [0127]    Preferably, the device is treated with the composition containing one or more of the oligonucleotides of this invention (e.g. solution or gel) for a sufficient period of time to allow adsorption. Both the concentration of the oligonucleotides of this invention in the solution or gel and the time of exposure depend on a number of factors, including the volume of the defect and the nature of the site to which it is applied, and should be adjusted accordingly. As the size of the defect increases, or when the site is other than a bone site, the concentration of the oligonucleotides and the time of pre-soaking should be increased. The treatment should preferably be for at least about 0.5 hour, depending on the factors mentioned above (more preferably at least about 1 hour, and most preferably 1-2 hours), before implantation. Also depending on the above considerations, the concentration of oligonucleotides in the composition should preferably be of at least about 0.1 mg/ml (more preferably of at least about 0.5-10 and up to 100 mg/ml). The treatment may consist of any mode by which the composition is applied to the device to deliver effectively the osteogenic oligonucleotides of this invention and the osteogenic cell source if necessary. Such treatment includes, for example, adsorption or impregnation, depending in part on the nature of the indication. The compositions containing the osteogenic oligonucleotides of this invention to be used in the therapy will be dosed in a fashion consistent with good medical practice taking into account the nature of the skeletal tissue deficiency to be treated, the species of the host, the medical condition of the individual patient, the presence of any other drug in the composition, the site of delivery of the agent, the method of administration, the scheduling of administration, and other factors known to practitioners. Because of differences in host response, significant site-to-site and patient-to-patient variability exists. For purposes herein, the “therapeutically effective amount” of the osteogenic oligonucleotides of this invention is an amount that is effective to induce bone growth, as defined above, at the site of skeletal tissue deficiency. 
         [0128]    As a general proposition, the osteogenic oligonucleotides of this invention are formulated and delivered to the target site at a dosage capable of establishing an oligonucleotide level equal or greater than about 0.1 mg/ml at the site. Typically, the oligonucleotide concentrations range from about 0.1 mg/ml to 12 mg/ml, preferably from about 1 to 4 mg/ml. These intra-tissue concentrations are maintained preferably by topical application and/or sustained release. 
         [0129]    As noted above, these suggested amounts of oligonucleotides are subject to a great deal of therapeutic discretion. The key factor in selecting an appropriate dose and scheduling is the result obtained. Clinical parameters to determine an endpoint include increase in bone formation and mass and in radiographically detectable bone height. Such measurements are well known to those clinicians and pharmacologists skilled in the art. 
         [0130]    The oligonucleotide composition is administered either locally to the site by any suitable means, including topical and continuous release formulation, or systemically, as needed. The oligonucleotides are generally combined at ambient temperature at the appropriate pH, and at the desired degree of purity, with a physiologically acceptable carrier, i.e., a carrier that is non-toxic to the patient at the dosages and concentrations employed. The carrier may take a wide variety of forms depending on the form of preparation desired for administration. 
         [0131]    For the preparation of a liquid composition suitable for impregnation of a device, the carrier is a suitable buffer, a low molecular weight (less than about 10 residues) polypeptide, a protein, an amino acid, a carbohydrate (including glucose or dextrans), a chelating agent such as EDTA, cellulose, or other excipients. In addition, the oligonucleotide composition is preferably sterile. Sterility is readily accomplished by sterile filtration through 0.2 micron membranes. The oligonucleotide will be ordinarily stored as an aqueous solution, although lyophilized formulations for reconstitution are acceptable. 
         [0132]    Generally, where the bone disorder allows so, one should formulate and dose the oligonucleotide for site-specific delivery, where the oligonucleotide is formulated into a sterile sustained-release composition suitable for local application to the desired site. 
         [0133]    For local application of the oligonucleotide composition, for example, in the case of a bone defect that is a crack, e.g., a union fracture; the carrier may be any vehicle effective for this purpose. For obtaining a gel formulation, the liquid composition is typically mixed with an effective amount of a water-soluble polysaccharide, polyethylene glycol, or synthetic polymer such as polyvinylpyrrolidone to form a gel of the proper viscosity to be applied topically. The polysaccharide is generally present in a gel formulation in the range of 1-90% by weight of the gel, more preferably 1-20%. The polysaccharide that may be used includes, for example, cellulose derivatives such as etherified cellulose derivatives, including alkyl celluloses, hydroxyalkyl celluloses, and alkylhydroxyalkyl celluloses, for example, methylcellulose, hydroxyethyl cellulose, carboxymethyl cellulose, hydroxypropyl methylcellulose, and hydroxypropyl cellulose; starch and fractionated starch, agar; alginic acid and alginates, gum arabic, pullullan, agarose, carrageenan, dextrans, dextrins, fructans, inulin, mannans, xylans, arabinans, chitosans, glycogens, glucans, and synthetic biopolymers, as well as gums such as xanthan gum, guar gum, locust bean gum, gum arabic, tragacanth gum, and karaya gum, and derivatives and mixtures thereof. The preferred gelling agent herein is one that is inert to biological systems, non-toxic, simple to prepare, not too runny or viscous, and one that will not destabilize the oligonucleotide held within it. Preferably the polysaccharide is an etherified cellulose derivative, more preferably one that is well defined, purified, and listed in USP, e.g., methylcellulose and the hydroxyalkyl cellulose derivatives, such as hydroxypropyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methylcellulose. Most preferred herein is methylcellulose. 
         [0134]    The polyethylene glycol useful for gelling is typically a mixture of low and high molecular weight polyethylene glycols to obtain the proper viscosity. For example, a mixture of a polyethylene glycol of molecular weight of 400-600 Dalton with one of molecular weight of 1,500 would be effective for this purpose when mixed in the proper ratio to obtain a paste. The term “water soluble” as applied to the polysaccharides and polyethylene glycols is meant to include colloidal solutions and dispersions. In general, the solubility of the cellulose derivatives is determined by the degree of substitution of ether groups, and the stabilizing derivatives useful herein should have a sufficient quantity of such ether groups per anhydroglucose unit in the cellulose chain to render the derivatives water soluble. A degree of ether substitution of at least 0.35 ether groups per anhydroglucose unit is generally sufficient. Additionally, the cellulose derivatives may be in the form of alkali metal salts, for example, the Li, Na, K, or Cs salts. 
         [0135]    In a preferred embodiment, the gel contains about 2-5% by weight methylcellulose and the oligonucleotide is present in an amount of about 10-1000 μg per ml of gel. More preferably, the gel consists of about 3% methylcellulose by weight, lactic acid to pH 5.0, and 20-200 μg per ml of oligonucleotide. 
         [0136]    For the preparation of a sustained-release formulation, the oligonucleotide is suitably incorporated into a biodegradable matrix or microcapsular particle. A suitable material for this purpose is a polylactide, although other polymers of poly (.alpha.-hydroxycarboxylic acids), such as poly-D-(−)-3-hydroxybutyric acid (EP 133,988A), can be used. Additional biodegradable polymers include poly(lactones), poly(acetals), poly(orthoesters) or poly(orthocarbonates). The oligonucleotide is also suitably mixed with a biodegradable protein carrier such as collagen, atelocollagen, or gelatin to form a carrier matrix having sustained-release properties; the resultant mixture is then dried, and the dried material is formed into an appropriate shape, as described in U.S. Pat. No. 4,774,091. 
         [0137]    The initial consideration here must be that the carrier itself, or its degradation products, are non-toxic in the target bone site and will not further aggravate the condition. This can be determined by routine screening in animal models of the target bone disorder or, if such models were unavailable, in normal animals. For examples of sustained-release compositions, see U.S. Pat. No. 3,773,919, EP 58,481A, U.S. Pat. No. 3,887,699, EP 158,277A, Canadian Patent No. 1176565, U. Sidman et al., Biopolymers, 22:547 (1983), and R. Langer et al., Chem. Tech., 12:98 (1982). 
         [0138]    Controlled delivery of the oligonucleotide to a site is also suitably accomplished using permeable hollow cellulose acetate fibers with the oligonucleotide placed in the site and removed 24 hours later or left for longer periods of time (U.S. Pat. No. 4,175,326). Also, acrylic resin strips or cast films can be impregnated with the oligonucleotide and applied to the affected site. In addition, narrow dialysis tubing can be filled with a solution of the oligonucleotide and placed so as to deliver it to the appropriate site. 
         [0139]    The composition herein may also suitably contain other osteogenetic factors such as IGF-I, TGF-beta 1, and PDGF. Such osteogenetic factors are suitably present in an amount that is effective for the intended purpose, i.e., to promote formation of bone. 
         [0140]    The invention will be better understood by reference to the following examples. They should not, however, be construed as limiting the scope of the invention. All literature citations are incorporated by reference. 
       Example 1 
     Materials and Methods 
       [0141]    The following materials and methods were generally used throughout the examples. 
       1) Oligonucleotides 
       [0142]    Oligonucleotides having phosphorothioate internucleotide linkages were purchased, purified by high-pressure liquid chromatography (HPLC), from Operon Technologies (Alameda, Calif.) or Annovis (Aston, Pa.) or Oligos Etc (Bethel, Me.). ODNs were suspended in depyrogenated water, assayed for LPS contamination using the Limulus test and kept at −20° C. until used. Purity was assessed by HPLC and PAGE assays. ODN preparations were used if LPS levels were undetectable. 
       2) Animal Experiments 
       [0143]    Young (8-12 weeks old) adult male Spragüe Dawley rats weighing about 350 g were used. Animals were anesthetized by intraperitoneal (i. p.) injection of a mixture of ketamine (50 mg/kg) and xilacine (5 mg/kg). After skin overlying the hind limb was shaved and sterilized. A 1.5 cm longitudinal incision was performed in the tibia forefront zone. To generate a defect in the bone, an osteotomy was made using a low-speed dental drill attached to a round diamond saw under saline irrigation. For the osteotomy, a site free of muscular insertions was selected 15 mm below the ankle. The wound was deep enough to reach the bone marrow. A single dose (as stated in each experiment) of ODN in 3 μl of methylcellulose 1% was introduced into the defect made in the right tibia. As a control, the same volume (3 μl) of vehicle was introduced into the defect made in the left tibia. Fracture callus formation was evaluated radiographically on days 0, 21 and 28. On day 28, animals were euthanized under ether atmosphere, and the tibias removed and photographed. After this, the tibias were fixed in 10% formol solution, decalcified in 10% EDTA solution, and embedded in paraffin. A longitudinal section of each tibia was cut, stained with hematoxilin/eosine and examined under a light microscope. 
       Example 2 
     Osteogenesis Stimulation by Oligonucleotides 
       [0144]    A rat femur tibial model was employed as described in Example 1. First, a total dose per defect of 60 μg of oligonucleotide was used. The oligonucleotide used in these experiments was IMT504. This oligonucleotide is 24 nucleotides long, its nucleotide sequence is 5′-TCATCATTTTGTCATTTTGTCATT-3′, and all the DNA (natural) phosphodiester bonds have been replaced with phosphorothioate bonds to protect it from enzymatic degradation. As example,  FIG. 1  shows radiographs corresponding to both tibias of an experimental rat. In the right tibia, were the bond defect has been filled with vehicle plus IMT504, radiodense material filling the defect can be observed as early as 3 weeks after initiation of the treatment. In this treated right tibia, the defect is no longer visible at week 5 after initiation of the treatment. On the other hand, the defect is clearly visible by week 5 in the untreated (control) left tibia.  FIG. 2  shows a photograph of the right (treated with IMT504) and left (untreated) tibia at the site where the experimental osteotomy was performed. As can be observed, the defect in the treated tibia appears completely filled with apparently normal bond while the defect in the control tibia is filled with spongy material corresponding to an incomplete ossification. The corresponding histological documentation can be seen in  FIG. 3 . In this figure the treated tibia shows well-formed bone tissue at the site where the osteotomy was performed. In contrast, in the untreated tibia the defect is still visible. 
       Example 3 
     Effect of the ODN Concentration in Osteogenesis Induction 
       [0145]    In order to evaluate the minimal amount of IMT504 necessary to obtain rapid ossification, a rat femur tibial model was employed as described in Example 1. Table 1 shows that filling the osteotomy with a gel containing at least 0.4 mg/ml of IMT504 is necessary to obtain rapid ossification even though some activity was observed in a concentration as low as 0.06 mg/ml. 
         [0000]    
       
         
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
             
             
               
                 IMT504 concentration 
                 0 
                 0.06 
                 0.4 
                 0.8 
                 1.5 
                 3 
                 6 
                 12 
                   
               
               
                 (mg/ml) 
               
               
                   
               
               
                 Ossification 35 days 
                 − 
                 +/− 
                 + 
                 + 
                 + 
                 + 
                 + 
                 + 
               
               
                 after operation 
               
               
                   
               
               
                 IMT504 (SEQ ID N o  2) 
               
             
          
         
       
     
       Example 4 
     Induction of Osteogenesis by ODNs with Different Composition 
       [0146]    Several of the components of the immune-system play a role in regulation of the osteogenic proccess (Shinoda K, Sugiyama E, Taki H, Harada S, Mino T, Maruyama M, Kobayashi M. Resting T cells negatively regulate osteoclast generation from peripheral blood monocytes. Bone. 2003 October; 33(4):711-20; Evans D B, Bunning R A, Russell R G. The effects of recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) on human osteoblast-like cells. Biochem Biophys Res Commun. 1989 Apr. 28; 160(2):588-95; Fujikawa Y, Sabokbar A, Neale S D, Itonaga I, Torisu T, Athanasou N A. The effect of macrophage-colony stimulating factor and other humoral factors (interleukin-1, -3, -6, and -11, tumor necrosis factor-alpha, and granulocyte macrophage-colony stimulating factor) on human osteoclast formation from circulating cells. Bone. 2001 March; 28(3):261-7.). Therefore, we investigated the effect of different kinds of immunostimulatory ODNs in the osteogenetic process. Table 2 shows that the best stimulation of the osteogenesis was obtained using immunostimulatory ODNs of the PyNTTTTGT class (Elias F, Flo J, Lopez R A, Zorzopulos J, Montaner A, Rodriguez J M. Strong cytosine-guanosine-independent immunostimulation in humans and other primates by synthetic oligodeoxynucleotides with PyNTTTTGT motifs. J Immunol. 2003 Oct. 1; 171(7)3697-704.). 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 Oligo- 
                   
                 Immunostimulatory 
                 Osteogenic 
                   
               
               
                 nucleotide 
                 Sequence 
                 activity 
                 activity 
               
               
                   
               
             
             
               
                 IMT022 
                 TGCTGCAA 
                 − 
                 +/−− 
                   
               
               
                   
                 AAGAGCAA 
               
               
                   
                 AAGAGCAA 
               
               
                   
               
               
                 IMT518 
                 TCGTCGAA 
                 +++ 
                 +/−− 
               
               
                 (CpG ODN) 
                 AAGTCGAA 
               
               
                   
                 AAGTCGAA 
               
               
                   
               
               
                 IMT504 
                 TCATCATT 
                 +++ 
                 +++ 
               
               
                 (PyNTTTTGT 
                 TTGTCATT 
               
               
                 ODN) 
                 TTGTCATT 
               
               
                   
               
               
                 IMT022 (SEQ ID No 8); 
               
               
                 IMT518 (SEQ ID No 106); 
               
               
                 IMT504 (SEQ ID No 2) 
               
             
          
         
       
     
         [0147]    These results indicate that ODNs with strong immunostimulatory activity are not necessarily strong stimulators of the osteogesis. However, the most active ODNs in osteogenesis are strongly immunostimulatory.