role of bone morphogenic proteins in periodontology.pptx

Bone morphogenic proteins

1. BONE MORPHOGENIC PROTEINS

2. C0NTENTS INTRODUCTION HISTORY DISCOVERY ISOLATION PURIFICATION CLASSIFICATION OF BMP & RECEPTORS MECHANISM OF ACTION CLONING OF rh BMP PRODUCTION OF rh BMP EFFECTS OF BMP ON BONE PERIODONTAL REGENRATION RIDGE AUGMENTATION MAXILLARY AUGMENTATION

3. INTRODUCTION Bone is the important tissue. A unique tissue , as it undergoes continous process of turnover and remodelling . More than 2,50,000 bone graft are performed annually in USA, thus makes bone 2 nd only to blood products as the most common type of graft.

4. Bone can be seen as consisting of three components: A mineral component which gives its structural integrity. A collagenous matrix component. A growth factor component which contains BMP activity

5. Osteoconductive : these materials which provide simply a scaffold effect. Osteogenic : these have growth factors. Osteoinductive : they have morphogens . What are morphogens ??? Morphogens are those substances which initiate the development of tissues by stimulating the undifferentiated cells to convert phenotypically .

6. Many growth factors have been isolated and tested for their capability. Growth factors act on pre-existing bone, their effect is limited in large bony defects. The advantage of utilizing morphogens in the regeneration of bone is the pre- existence of the osteoprogenitor cells in the area is unnecessary . Therefore , the amount of new bone formation is essentially limitless .

7. Bone morphogenic proteins are only morphogens . Bone morphogenic proteins (BMPs) represent a unique set of differentiation factors that induce new bone formation at the site of implantation instead of changing the growth rate of pre-existing bone

8. HISTORY AND DEVELOPMENT Heterotopic bone formation It has been observed that extra skeletal tissues under certain pathologic conditions may ossify. This is extra-skeletal bone is called hetertopic or ectopic bone” is in fact true bone, containing “all the morphologic and metabolic features of orthotopic bone, including bone marrow ( Ekelund et al, 1991).

9. DISCOVERY

10. In 1938, Levander implanted living bone fragments 1 – 1.5cm in length either SC or IM. These fragments were first treated by scraping away the periosteum, and some specimens a superficial layer of bone was remove. Hence, upon obtaining regenerated bone Levander was able to show that neither periosteum nor cells on the surface or within the graft were responsible for new bone growth. Next experiment he injected alcohol extracts of bone.

11. Lacroix in 1945 stated that bone formation was due to an induction phenomenon and originated from a substance or a group of substance within the cartilage which he suggested calling osteogenin . Heinen (1949) stated that this hypothetical osteogenic substance could not be proved and stated that is was unfortunate that investigations studying this hypothesis had used mainly rabbit, a species which had manifested a high incidence of ectopic cartilage and bone in many organs, following wide variety of experimental procedures

12. Urist and coworkers “discovered” that control samples of untreated decalcified bone implanted into muscle pouches of rabbits and rats resulted in new cartilage and bone formation. This led to the hypothesis of bone formation by autoinduction in which an inductor cell (a wandering histiocyte ) acts upon a induced cell (a fixed histiocyte or perivascular connective tissue cell) causing it to differentiate into either an osteoprogenitor or chondroprogenitor cell ( Urist , 1965, 1967).

13. ISOLATION Bone decalcified in cold (2 C) dilute (0.6N) Hcl for less than 3 to 5 days, followed by washing in 0.15N NaCl or 70% alcohol produced the most positive results.

14. TRANS MEMBRANE DIFFUSION An experiment designed to test the morphogenetic activity of various size of bone particles They used preparations of bone matrix pulverized in a freezer mill at –199 C in order to minimize the protein damage resulting from heat.

15. Diffusion chambers made up of cellulose acetate membranes with 150 um thick & pore size of 0.45 um were used. Particle size of 400- 1000 um resulted in bone.

16. The results were that the amount of new bone formation was shown to be inversely proportional to the distance which the bone morphogenetic property must travel. This experiment provided evidence of a rapidly diffusible bone morphogenetic property to exist.

17. PURIFICATION Isolation and purification of BMP has been difficult due to the fact that so little of it is present in bone as compared to other non-collagenous proteins and also because of their relative insolubility   20µg of protein with bone inductive activity was found in 10kg of bovine bone WANG 1988 & WOZNEY 1988

18. BONE MORPHOGENETIC FAMILY Based on their amino acid sequences, these proteins form a sub group of the transforming growth factor –beta superfamily of growth and differentiation factors. There are 15 BMP discovered.

19. TYPES OF BMP BMP-1 : Protease (member of the astacin family) Activates BMPs ; not osteoinductive ; May be involved with Langer- Giedion syndrome

20. BMP-2 : Osteoinductive & embryogenesis; Differentiation: osteoblasts , adipocytes , chondrocytes; may influence osteoclast activity ;neuronal differentiation Repair of long bone, alveolar cleft, spine fusion; augmentation of maxillary sinus; located in bone, spleen ,liver, brain, kidney, heart, placenta.

21. BMP-3 / osteogenin : Osteoinductive, promotes chondrogenic phenotype; located in lung, kidney, brain intestine.   BMP-4 : Osteoinductive; Embryogenesis: Fracture repair; Overexpression in fibrodysplasia ossificans progressiva ; Located in apical ectodermal ridge, meninges , lung, kidney, liver

22. BMP-5 : Osteoinductive,Embryogenesis . Located in lung, kidney, liver BMP-6: Not osteoinductive , Embryogenesis, Neuronal maturation, Regulates chondrocyte differentiation Found in lung, brain, kidney, uterus, muscle, skin     BMP-7 : OSTEOGENIC PROTEIN-1 Osteoinductive, embryogenesis

23. Repair of long bone, Alveolar bone, Spine fusion, Differentiation of osteoblasts , Chondroblasts , Adipocytes Located in adrenal glands, bladder, brain, eye, heart, kidney, lung, placenta, spleen, skeletal muscle BMP-8/OP -2: Osteoinductive;embryogenesis ; spermatogenesis(mouse )  BMP-8B:OP-3: I nitiation and maintenance of Spermatogenesis

24.   BMP-9: Osteoinductive; stimulates hepatocyte proliferation, hepatocyte growth& function.   BMP-12 & BMP-13 : Inhibition of terminal differentiation of myoblasts  

25. BMP RECEPTORS BMP’s bind to two types of serine threonine receptors – BMPR-I, BMPR-II receptors. Both types of receptors are necessary to transduce BMP signals Ligand bind to BMPR-II, which in turn activates BMPR-I. BMPR-I receptors also bind BMP directly in the absence of BMPR-II receptor.

26. Type I receptors important target is the signaling protein SMAD which is phosphorylated by the Type I receptor on a serine residue. SMAD PROTEINS : These are signal transducing molecules for the TGF- β super family.

27. WHAT REGULATES THEIR PRODUCTION???

28. ON OSTEOBLASTS KING 1997: ability to stimulate intramembranous bone formation without endochondral intermediate. The predictability of bmp in stimulating new bone is greater than autogenous bone & growth factors.

29. TGF-b, IGFs, and FGFs all affect the already differentiated bone-forming cells present in the bone, causing them to divide and/or increase secretion of extracellular matrix molecules. On the other hand, rhBMP-2 will affect the precursor cells, cells from the marrow environment and the soft tissue surrounding the defect site, to infiltrate the defect area and differentiate into cartilage and bone cells.

30. ON CEMENTOBLAST TENORIO 1994 ability of BMP -2 to stimulate cementogenesis is suggested by similarity between cementoblast & osteoblast. IS THERE A SIMILARITY BETWEEN OSTEOBLAST AND CEMENTOBLAST?????

31. Evidence by Andreasen 1981 & Lindskong 1983 the reparative cementum resembled alveolar bone. Similarity in staining patterns between osteoblast and cementoblast. all these observations suggest that repartive cementum is formed from osteoprogenitor cells.

32. IS IT CELLULAR CEMENTUM OR ACELLULAR CEMENTUM???? KING in 1997 formation of cellular cementum when BMP used in treatment of fenestration. BEERTSEEN 1998 formation of reparative acellular cementum in wound healing sites. BERGLUNDH LINDHE 1997 - rh BMP 2 studies evaluated healing on furcation defects in dogs showed that acellular cementum formation occurred in contrast to defects treated with GTR where cellular cementum formation developed.

33. RIPAMONOTI 1994 Documented periodontal regeneration after surgical implantation of BMP into 12 surgically induced furcations defect. Sharpey’s fibers were seen to unite new cementum to regenerated bone. RIPAMONOTI 1996 Demonstrated CEMENTOGENESIS after implantation of hOP-1/BMP-7 in baboons after two months. They also suggested that presence of exposed dentin directs cementum formation .

34. RIPAMONOTI 2002 demonstrated cementogenesis & alveolar bone regeneration after placement of h OP -1 in periodontally induced furcation defects whose root surfaces were exposed to pathogens for a long time. He also stated that induction of cementogenesis is a pleiotropic function of h OP -1 ( KINOSHITA ET AL 1997)

35. TAKEN TOGETHER ALL THESE REPORTS SUGGEST THAT BMP DO PROMOTE ACELLUAR CEMENTUM BUT FURTHER STUDIES ARE NECESSARY

36. BMP EFFECTING ON VARIOUS TYPES OF DEFECT p

37. EFFECT OF DOSE GIANNOBILE 1998 reported that increasing the dose led to increase in amount of regenration .

38. ROOT CONDITIONING LEE et al 1995 partial root deminrealization augments therapeutic effect of BMP-2. JASON 1995 root conditioning with rh BMP-2 enhanced cementogenesis. KING 1998 root conditioning with BMP impaired osteogenesis .

39. Less bone formation occurred when rh BMP was applied in presence of root conditioning .

40. PERIODONTAL REGENERATION DFDBA bone graft contains BMP but the limatation is that the amount obtained is very less. So cloning of BMP was done to produce large amounts .

41. CLONING OF rhBMP

42. PRODUCTION OF rh BMP2  

43. DELIVERY SYSTEM An ideal carrier should be Easy to manipulate Non immunogenic & resorbable Provide space & support the gingival flap Not impede mesenchymal cell differentiation & vascular invasion.

44. Collagen Type1 bovine collagen most commonly used. Osteoconductive substratum & high affinity for BMP. Takoka et al 1991 found telopeptide free collagen superior to conventional collagen. Sustained release with collagen sponge

45. CANINE DEMINERALISED BONE MATRIX (DBM) Cook et al1994,Sciadini 1997 demonstrated suitability of DBM extracted with GuHCl as a carrier for BMP. Immunogenicity remains a problem.

46. SYNTHETIC CALCIUM PHOSPHATE PUTTY – Osteoconductive,biocompatible with affinity to bone. Wozney et al Hardens into cement form in 20 min & resorbs after 26 weeks.

47. SYNTHETIC POLYMERS Polyglycolic acid,polylactic acid Dose dependent sustained release pattern is seen.( Winn et al 1999).

48. BMP IN POST FETAL BONE INDUCTION NORMAL BONE HEALING BONE HEALING AFTER BMP PLACEMENT BONE FORMATION DAY10-12 DAY 5 CARTILAGE FORMATION DAY 5 BONE AND CARTILAGE ARE FORMED AT THE SAME TIME.

49. CAMPBELL 1992/ NAKASE 1994 suggested that BMP is liberated in the fracture gaps. It regulates the proliferation and differentiation of mesenchymal cells like in embryonic limb bud. YAN 1990 Monoclonal antibodies indicated the presence of BMP in periosteum . CAMPBELL 1992 there are low levels of BMP serves as reserve source of morphogen

50. PERIODONTAL REGENERATION Huang 2005 demonstrated new cementum with h bmp – 6. RIPAMONOTI 2001 demonstrated that h OP showed cementogenesis & h BMP2 induced bone formation after binary applications of the above respectively

51. KINGS & HUGHES 2001 BMP can stimulate progenitor cells located not only residual PDL but also in blood clot within PDL wound, adjacent endosteal spaces & beyond PDL defects.

52. WIJESKO 2002 h BMP-2 WAS OSTEOGENIC WIJESKO 2004 periodontal regeneration h bmp - 12 SORENSEN 2004 tooth replantation with h bmp failed to form new pdl CHEN 2008 (rhBMP-2) yields unhinged periodontal relationship

53. Saito A , 2009 June evaluated local conditions in recipient sites that affected periodontal regeneration following BMP implantation in experimentally induced horizontal defects in dogs. following BMP implantation did not affect connective tissue attachment, cementum regeneration, and downgrowth of junctional epithelium.

54. BMP IN IMPLANTS RUTHEFORD 1992 Bone formation around implants. WANG 1994 Confirmed COCHRAN 1999 Rh BMP 2 can stimulate bone onto & around implants. SORENSEN 2007 Bone formation at rhBMP-2-coated titanium implants LAN J 2006 The combination of rhBMP-2 and rhbFGF showed faster growth of new bone at 8 months.

55. LUTZ R 2008 T his study show a significantly positive effect of liposomal vector/BMP-2 on bone regeneration and osseointegration in bony circumferential peri -implant defects.

56. BMP IN MAXILLARY SINUS LIFT NEVINS 1996 Van den berg 2000 indicate that the OP-1 device has the potential for initiating bone formation in the human maxillary sinus within 6 months after a sinus floor elevation BOYNE .P 2005 did a first RCT Demonstrated de novo tissue formation after rh BMP was placed in humans.

57. BMP IN RIDGE AUGMENTATION HOWELL 1997 used collagen sponge with rh BMP for local ridge augmentation. Bone formation was not present. But the study demonstrated that rh BMP was used safely in patients. Wikesjo 2008 rhBMP-2 coated onto titanium porous oxide implant surfaces induced clinically relevant local bone formation including vertical augmentation of the alveolar ridge and osseointegration .

58. Jung RE 2003 concluded that the combination of the xenogenic bone substitute mineral with rhBMP-2 can enhance the maturation process of bone regeneration and can increase the graft to bone contact in humans. rhBMP-2 has the potential to predictably improve and accelerate guided bone regeneration therapy.

59. TOOTH MORPHOGENESIS 6 different BMPS are expressed and their expression is different. In root morphogenesis they have localizied BMP3 & OP-1 suggesting that they play important role in cementogenesis

60. CONCLUSION THE CAPACITY OF BMP TO INTIATE A PROGRAMMED CELLULAR CASCADE THAT RESULTS IN INDUCTIION OF BONE IS A CONSERVED PROCESS UTILIZED IN EMBRYONIC DEVELOPMENT, RECAPITULATED IN POSTFETAL OSTEOGENESIS & CAN BE REXPLOITED FOR THERAPEUTIC TISSUE REGENERATION.