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P.Prathahini,
IIIrd MDS
Tissue engineering and
Periodontal Regeneration
Introduction
• See the hole ,fill it ,with anything
- Perio 2000 vol 50.
Principle Objective …
“To re-create functional, h...
Periodontal Regeneration
• Appropriate cell types & Signals
• Local environment
– Recruitment of the right cells and
preve...
Epithelial cells –
junctional
epithelium
Fibroblasts –
gingival
&periodontal
ligament fibres
Blastic cells -
Osteoblasts f...
To say periodontal regeneration has occurred 4
criteria should be fulfilled
• Functionalepithelialseal
• Newconnectivetiss...
Reasons for Failures in Periodontal
Regeneration technique
• Formation of a long junctional epithelium;
• Inadequate seal ...
- Tissue engineering is defined as the reconstruction of living
tissues to be used for the replacement of damaged or lost
...
• Sixteenth century, Tagliacozzi of
Bologna, Italy,
“De Custorum Chirurigia per
Insitionem,”
• 1970 – WT Green (Orthopaedi...
Key components
Scaffold
Progenitor cells
Biosignals
Diagrammatic representation of arteriovenous
shunt loop model in the rat – Mian R et al 2000
Artery
Venous graft
Hole of i...
Two main criteria for successful
tissue engineering
Biomechanical properties
• Scaffold,
• Architectural geometry
• Space-...
Stem Cells
Primal undifferentiated cells
that retain the ability to
produce an identical copy of
themselves when they divi...
Potency
The potency specifies the differentiation potential of the
stem cell.
• Totipotent stem cells
• Pluripotent stem c...
Key events in stem cell research
• 1960s - Joseph Altman and Gopal Das presented
evidence of adult neurogenesis, ongoing s...
Key events in stem cell research
• 1997 - Leukemia was shown to originate from a
haematopoietic stem cell, the first direc...
Types of Stem cells
Adult
stem
cells….
Embryonic
stem cells
in vitro
ADVANTAGES
The ability to
examine the material
as it is formed and to
perform specific
measurements prior
to impl...
in vivo
ADVANTAGES
Tissue formation takes
place under the influence
of physiologic mechanical
environment.
Incorporation o...
I) Hematopoietic stem cells
2) Bone marrow -
stem cells
-Friedenstein et al 1976
-All cell lineages
- Mesenchymal fibrobla...
Locally derived uncommitted cells
• Periodontal ligament stem cells
• Dental pulp stem cells
- Cell surface markers ( Gron...
Periodontal ligament stem cells
• Highly fibrous and vascular…. High turn over
rates
- Cementum like mineralized structure...
• Fibroblastic colony forming units …..greater in
PDL stem cell (170) as against the bone marrow
stromal cell (14).
– Prop...
Soe et al, 2004 Isolated a population of multipotent stem
cells in human PDL derived mesenchymal
stromal cells.
Liu et al,...
Growth potential of pdl stem cells
• Differential proliferative capacity…
- 80%.... Failed beyond 20 population doublings....
Characterization and origin of Periodontal
stem cells
• Differentiated from Dental Follicle during embryogenesis….
• Putat...
Scaffolds/Matrices
• The extracellular matrix consists of
proteins and glycoproteins such as
collagens, laminins, fibronec...
Provides...
• Hydration for cells
• Elastic network
• Cell attachment, proliferation &
differentiation
• Store & protect G...
Interactions between ECM & cell surafce recptors
Embryonic
morphogenesis
Cell surface
receptor
Feedback
to ECM
Gene
expres...
Area code hypothesis...
• Hood L et al 1977
• The presence of a recognition system that guides cell
positioning
ECM protei...
Ideal properties
• Biocompatibility (no immunogenicity)
• Space maintenance
• Mechanical rigidity
• Degradability-in a pha...
Natural
• Collagen, hyaluronan, chitosan.
Gelatin, fibrin, alginate, biocover &
Matrix extracts like Matrigel.
• Biodegrad...
Synthetic
• Poly(glycolic acid), poly(lactic acid) or
poly(lacticacid)/poly(glycolic acid) and
their copolymers, poly(p-di...
Collagen sponge scaffold +
gelatin microspheres loaded
with FGF 2 in alveolar bone
defects - Nakahara et al. 2004
Vascular...
Tissue engineered scaffolds in periodontal therapy
Physical forces determines longterm composition,
quality, volume of the tissue construct ....
- Mechanical forces as
regul...
Functional engineering....
- The aim of improving understanding of the role that mechanical
factors play in tissue regener...
Competence factors (PDGF, FGF)
Progression factors
(IGF-I,
Dexamethazone)
JE = 1-6 days
Osteoblast lineage = 20-30 daysBio...
BMP’s
PDGF
BMP’s
IGF I,II
TGFβ
IGF I,II
TGFβ
Cell differentiation
Transforming Growth factors
• Major growth factors in bone matrix
• Superfamily of bone morphogenic proteins
• A peptide s...
Contrella M et al 1987
TGF -β
Smad
signalling
pathway
Migration
of
Osteogenic
progenitor
cells
Proliferate
Increases
osteo...
Miyazona K et al 2005
Cell
BMPs + BMPR1
BMPR2
Increases
cbfX1 gene
exp
Increases MSX
gene exp
Epithelial &
mesenchymal
int...
BMPs acts on the pluripotent cells,
increases the committment &
differentiation of osteoblasts.
- Katagiri et al 1990
BMPs...
Insulin like growth factors I & II
• Synthesized primarily in liver and locally by osteoblasts.
• Mediate effect of system...
IGF + PDGF increases periodontal regeneration
- Lynch SE et al 1989
IGF I + BMP 2 act synergistically on OSTERIX
- Celil A...
Fibroblast Growth Factors
• Autocrine / Paracrine regulators of bone formation
• Stimulate chemotaxis, proliferation & mat...
Bone regeneration
GFs
IGF FGF
VEGF TGF PDGF
TNF-alpha , IL-1beta
Bone regeneration, remodelling & repair
BMPs,Cytokines, G...
Role of vasculature and neovascularization
in tissue engineering
• Cell survival…
– O2 Supply
– Nourishment
– Disposal of ...
Vasculature = 1) vasculogenesis – denovo formation
2) angiogenesis – mature network
Major angiogenic factors – FGF, PDGF a...
Vascular endothelial growth factor
• 6 proteins – VEGF A,B,C,D,E and placental GF
• Spliced forms like VEGF 121, 165,189
•...
Vascular endothelial growth factor
• Mouse model ; Fracture healing & cortical defect model;
- Street J et al 2002
• Major...
Platelet derived growth factor
• 3 isoforms ( AA,AB, BB); receptors a & b;
• Chemotactic effect on osteoblast & Ct cells
-...
Platelet derived growth factor
• PDGF +βTricalcium phosphate GEM21S
rh PDGF + freeze dried bone allograft
Excellent result...
Applications
•Cell therapy
Gene therapy
“Gene therapy is the insertion of genes into an
individual's cells and tissues to treat a disease, and
heredi...
• Transformation of ..
• Somatic cells
• Germ line cells (Sperm, Ova & stem Cells)
ex vivo
(where cells are modified outsi...
In Periodontics.....
A field of biomedicine.
• Not applied with success in periodontics
– Gene therapy Technology … far fr...
Gene enhanced TE...
Delivery of Therapeutic protein-like growth factor.
-short life (a few hours).
• This is due to proteo...
Studies in periodontal tissue engineering
• Sankaranarayanan S et al 2013, in a 23-year female patient
with advanced perio...
Studies in periodontal tissue engineering –
Reviewed by Elena A. Trofin et al 2013
• 7 case reports (for a total of 22 pat...
Studies in periodontal tissue engineering –
Reviewed by Elena A. Trofin et al 2013
• Cultured mandibular periosteum-derive...
Future directions in periodontics...
1. Gene Therapeutics-Periodontal Vaccination
2. Genetic Approach to Biofilm Antibioti...
Cell sheet engineering – Okano et al 1993
• Temperature responsive culture
dishes
• At 37 degree celsius ; adhere &
prolif...
Cell sheet engineering
Artificial salivary gland
Baum BJ et al
Tissue engineering for dental implants –
Biomimetic materials
Biomimetic Ca-P coatings
Both the superior mechanical proper...
Benefits Of The Biomimetic Approach Over Plasma-
sprayed Hydroxyapatite…
Albumin
Plasma protein and plays a fundamental role
in the transport of other proteins and
functional molecules in the blo...
BMP’s
rhBMP-2 incorporated into Ca-P
coatings
Combination of biomimetic Ca-P
coatings and osteoinductive agents
can provid...
Bisposphonates
Incorporated into Ca – P coatings
• Osteoclast inhibition
• Reduced bone turnover
• Increased bone mass
• I...
• To Master the art of recreating functional viable tissues in
the laboratory…..translate the knowledge ….to population
at...
Smile if you
think science is
real .....
Tissue engineering and periodontal regeneration
Tissue engineering and periodontal regeneration
Tissue engineering and periodontal regeneration
Tissue engineering and periodontal regeneration
Tissue engineering and periodontal regeneration
Tissue engineering and periodontal regeneration
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Tissue engineering and periodontal regeneration

periodontal regeneration and advances in tissue engineering for regeneration of periodontium

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Tissue engineering and periodontal regeneration

  1. 1. P.Prathahini, IIIrd MDS Tissue engineering and Periodontal Regeneration
  2. 2. Introduction • See the hole ,fill it ,with anything - Perio 2000 vol 50. Principle Objective … “To re-create functional, healthy tissues and organs in order to replace diseased, dying, or dead tissues”
  3. 3. Periodontal Regeneration • Appropriate cell types & Signals • Local environment – Recruitment of the right cells and preventing the wrong cell (Local Environment includes Cementum matrix & C.E.J). - Affects cell migration ,adhesion, proliferation & differentiation.
  4. 4. Epithelial cells – junctional epithelium Fibroblasts – gingival &periodontal ligament fibres Blastic cells - Osteoblasts for Alveoalr bone, cementoblasts for cementum Cells Growth factors – FGF-1 & 2, IGF-1&2, BMP, EGF,Pdgf Adhesion molecules – fibronectin, osteopontin , laminin, bsp, collagens, CAP Structural proteins - Types I,III,V, XII and XIV collagens, Proteoglycans, Hyaluran, tenascin, non- collagenous proteins, osteonectin, dentin/enamel proteins Molecules
  5. 5. To say periodontal regeneration has occurred 4 criteria should be fulfilled • Functionalepithelialseal • Newconnectivetissueattachment • Acellularextrinsicfibercementum • Alveolarboneheightrestored
  6. 6. Reasons for Failures in Periodontal Regeneration technique • Formation of a long junctional epithelium; • Inadequate seal ; • Wound closure • Restriction of regeneration. • Precise definition • Sufficient discrimination • Infection
  7. 7. - Tissue engineering is defined as the reconstruction of living tissues to be used for the replacement of damaged or lost tissue/organs of living organisms and is founded on the principles of cell biology, developmental biology and biomaterials science (Narem R. et al.,1995 ; Rosso F. et al., 2004; - “an interdisciplinary field that applies the principles of engineering and life sciences towards the development of biological substitutes that restore, maintain, or improve tissue function or a whole organ" Langer and Vacanti Tissue engineering
  8. 8. • Sixteenth century, Tagliacozzi of Bologna, Italy, “De Custorum Chirurigia per Insitionem,” • 1970 – WT Green (Orthopaedic surgeon) – created cartilage. • 1986 – Karl Meyer - created a skin substitute by using a collagen matrix • Dr.Langler - designed appropriate
  9. 9. Key components Scaffold Progenitor cells Biosignals
  10. 10. Diagrammatic representation of arteriovenous shunt loop model in the rat – Mian R et al 2000 Artery Venous graft Hole of insertion of vessel loop Vein Transparent chamber Femoral vessels Leg
  11. 11. Two main criteria for successful tissue engineering Biomechanical properties • Scaffold, • Architectural geometry • Space-maintaining properties Biological functions • Cell recruitment, proliferation, survival in culture and at the site of implantation, • Neovascularization • Delivery of morphogenetic-, regulatory- and growth factors
  12. 12. Stem Cells Primal undifferentiated cells that retain the ability to produce an identical copy of themselves when they divide (clone) and differentiate into other cell types.
  13. 13. Potency The potency specifies the differentiation potential of the stem cell. • Totipotent stem cells • Pluripotent stem cells • Multipotent stem cells • Unipotent stem cells
  14. 14. Key events in stem cell research • 1960s - Joseph Altman and Gopal Das presented evidence of adult neurogenesis, ongoing stem cell activity in the brain; their reports contradict Cajal's "no new neurons" dogma are largely ignored • 1963 - McCulloch and Till illustrate the presence of self-renewing stem cells in mouse bone marrow • 1968 - bone marrow transplant between two siblings successfully treats SCID • 1978 - haematopoietic stem cells are discovered in human cord blood • 1981 - mouse embryonic stem cells are derived from the inner cell mass • 1992 - neural stem cells are cultured in vitro as neurospheres • 1995 - President Bill Clinton signs into law the Dickey Amendment which makes it illegal for Federal money to be used for research where stem cells are derived from the destruction of the embryo.
  15. 15. Key events in stem cell research • 1997 - Leukemia was shown to originate from a haematopoietic stem cell, the first direct evidence for cancer stem cells • 1998 - James Thomson and coworkers derive the first human embryonic stem cell line at the University of Wisconsin-Madison. • 2000s - several reports of adult stem cell plasticity are published • 2003 - Dr. Songtao Shi of NIH discovers new source of adult stem cells in children's primary teeth • 2004-2005 - Hwang Woo-Suk claims to have created several human embryonic stem cell lines from unfertilised human oocytes. The lines are later shown to be fabricated • July 19, 2006 - President George W. Bush votes a bill which would have allowed Federal money to be used for research where stem cells are derived from the destruction of the embryo
  16. 16. Types of Stem cells Adult stem cells…. Embryonic stem cells
  17. 17. in vitro ADVANTAGES The ability to examine the material as it is formed and to perform specific measurements prior to implantation. DISADVANTAGES - The absence of a physiologic & mechanical environment during the formation of tissue in vitro. - Union of the implanted tissues with the host organ requires remodeling – degradation and new tissue formation at the interface of implant with the host tissue.
  18. 18. in vivo ADVANTAGES Tissue formation takes place under the influence of physiologic mechanical environment. Incorporation of the tissues being formed with the surrounding structures. DISADVANTAGES Regenerating tissues may be dislodged or degraded by the mechanical forces normally acting at the site, before the regenerating tissue is fully formed and incorporated.
  19. 19. I) Hematopoietic stem cells 2) Bone marrow - stem cells -Friedenstein et al 1976 -All cell lineages - Mesenchymal fibroblasts cells isolated - Specific surface markers
  20. 20. Locally derived uncommitted cells • Periodontal ligament stem cells • Dental pulp stem cells - Cell surface markers ( Gronthos & co workers 2005) The dental pulp stem cells represent a clonogenic and highly proliferative cell population - Densely calcified nodules = in vitro. - Dentin like and dentin sialo-phospho- protein rich mineralisation = Invivo
  21. 21. Periodontal ligament stem cells • Highly fibrous and vascular…. High turn over rates - Cementum like mineralized structure formed in vitro… Progenitor cells ….identified in vivo cell kinetic studies… • Enriched locations like around the blood vessels • Exhibit stem cell features – Small size – Responsiveness to stimulating factor – Slow cycle time. Most compelling evidence : McCulloch and coworkers 1985,1987,1995,1996
  22. 22. • Fibroblastic colony forming units …..greater in PDL stem cell (170) as against the bone marrow stromal cell (14). – Propensity …or ….difference in turn over rate.
  23. 23. Soe et al, 2004 Isolated a population of multipotent stem cells in human PDL derived mesenchymal stromal cells. Liu et al, 2008 Autologous periodontal ligament derived mesenchymal stromal cells promoted healing of experimental periodontitis in mini-pigs Studies
  24. 24. Growth potential of pdl stem cells • Differential proliferative capacity… - 80%.... Failed beyond 20 population doublings. • Pdl Stem cells Versus the Bone marrow stem cells .. - 30% higher osteogenic potential ( Yu BH et al 2014) - BMSCs owned the stronger immunomodulation in local microenvironment via anti-inflammatory functions, compared to PDLSCs. (Zhang J et al 2014) • Finite lifespan of Pdl stem cells… – Postnatal stem cells (Adult stem cells) – Embryonic stem cell…virtually immortal • Genetic manipulation can be done with caution..
  25. 25. Characterization and origin of Periodontal stem cells • Differentiated from Dental Follicle during embryogenesis…. • Putative cell marker .. STRO-1.. Common – Isolation using immunomagnetic …fluorescence activated cell selection. • Share common expression of cell marker CD146 • McCulloch et al……presence of perivascular progenitor cells in Pdl
  26. 26. Scaffolds/Matrices • The extracellular matrix consists of proteins and glycoproteins such as collagens, laminins, fibronectin, and proteoglycans and also the polysaccharide hyaluronic acid. Composition , organisation & distribution of extracellular matrix Simple mixing Cell isolation & expansion Cell on matrix New tissue
  27. 27. Provides... • Hydration for cells • Elastic network • Cell attachment, proliferation & differentiation • Store & protect Growth factors from degradation
  28. 28. Interactions between ECM & cell surafce recptors Embryonic morphogenesis Cell surface receptor Feedback to ECM Gene expression ECM Receptor ligand binding Receptor GF binding Presenting GF , Cytokines Storage Pool Modulation of ECM Intracellular Dynamic reciprocity ECM Cytoskeleton
  29. 29. Area code hypothesis... • Hood L et al 1977 • The presence of a recognition system that guides cell positioning ECM proteins • RGD domains in fibronectin, vitronectin, YIGSR domain - laminin, and GER domain – type I collagen Cell surface receptors • Integrins, syndecan , CD44, thrombomoduli n , laminin binding protein , CD36, and matrikines Cell adhesion MMPs – breakdown and remodellin g of ECM...
  30. 30. Ideal properties • Biocompatibility (no immunogenicity) • Space maintenance • Mechanical rigidity • Degradability-in a phased manner • Mechanical structure-three dimensional structure with sufficient porosity , surface roughness,greater surface energy,and availability of surface molecules.
  31. 31. Natural • Collagen, hyaluronan, chitosan. Gelatin, fibrin, alginate, biocover & Matrix extracts like Matrigel. • Biodegradable and non-toxic • Possess known cell binding sites. • Disadvantages – Immunogenicity , speed of degradation and limited ability to tailor certain specific properties.
  32. 32. Synthetic • Poly(glycolic acid), poly(lactic acid) or poly(lacticacid)/poly(glycolic acid) and their copolymers, poly(p-dioxanone) and copolymers trimethylene carbonate • Hydroxyapatite, calcium sulfate, and tricalcium phosphate - Osteoconductive • Bioactive glass – silicon network structure • Can modify the strength, pore size and stability. • Low pH hinder the cell growth Bioactive glass
  33. 33. Collagen sponge scaffold + gelatin microspheres loaded with FGF 2 in alveolar bone defects - Nakahara et al. 2004 Vascularization, osteogenesis, and recovery of periodontal ligament function after 4 weeks. Collagen sponges + periodontal ligament cells = cementum had uniformly regenerated along the root surface of bony defects in dog teeth Sculean et al. 2003, reported that the application of bovine derived xenograft and bioresorbable collagen in patients with periodontal defects resulted in significant improvement, with reduction of periodontal probing depth and clinical attachment levels observed 1 year post-treatment. Studies
  34. 34. Tissue engineered scaffolds in periodontal therapy
  35. 35. Physical forces determines longterm composition, quality, volume of the tissue construct .... - Mechanical forces as regulators of tissue growth, stem cell lineage commitment and differentiation, polarity, motility, contractility & apoptosis.
  36. 36. Functional engineering.... - The aim of improving understanding of the role that mechanical factors play in tissue regeneration. - Mechanical signals as key regulators of the cell behaviors required for successful engineered tissue growth. - Bioreactors are already being developed that are able to apply lineage-specific mechanical signals to populations of stem cells • Rigid substrate – Support high level isometric tension • Flexible substrate – Cannot resist forces - Turn off growth & differentiation
  37. 37. Competence factors (PDGF, FGF) Progression factors (IGF-I, Dexamethazone) JE = 1-6 days Osteoblast lineage = 20-30 daysBiosignals
  38. 38. BMP’s PDGF BMP’s IGF I,II TGFβ IGF I,II TGFβ Cell differentiation
  39. 39. Transforming Growth factors • Major growth factors in bone matrix • Superfamily of bone morphogenic proteins • A peptide synthesized & secreted in cell culture • Increases the pool of committed osteoblasts • Prevents long junctional epithelium formation • Increases osteoblasts chemotaxis
  40. 40. Contrella M et al 1987 TGF -β Smad signalling pathway Migration of Osteogenic progenitor cells Proliferate Increases osteoblasts pool Depends on dose & local environment. At high concentrations of TGF -β Inhibits DNA synthesis Inhibits osteoblasts Maeda et al 2004
  41. 41. Miyazona K et al 2005 Cell BMPs + BMPR1 BMPR2 Increases cbfX1 gene exp Increases MSX gene exp Epithelial & mesenchymal interaction Increases gene exp of ALP, osteocalcin Matrix formation & mineralization Bone morphogenic proteins •20 members., Eg – BMP 2,4,7 •BMP-2 differentiation factor for bone & cartilage precursor cells during osteogenesis and bone regeneration • BMP 5 through ActRIA inhibits matrix synthesis • Induce ectopic bone formation •Drive endochondral ossification
  42. 42. BMPs acts on the pluripotent cells, increases the committment & differentiation of osteoblasts. - Katagiri et al 1990 BMPs shown formation of bone nodules invitro... - Chen TL et al 1991 Gene expression studies Adenovirus vector + BMP-7 Robust osteogenic response Franceschi et al 2000 Limitations: - No pdl fibre formation in perpendicular direction and no acellular cementum formation - No role in osteoblast induction
  43. 43. Insulin like growth factors I & II • Synthesized primarily in liver and locally by osteoblasts. • Mediate effect of systemic hormones (Eg., GH), cytokines (IL-1α) & morphogens (BMPs) in bone formation & healing. • Increases proliferation effects of osteoblasts. • Local regulator of bone turnover • IGF -I more potent • IGF –I upregulates the osteoblast associated transcription factor OSTERIX but not cbfx1 & Runx2
  44. 44. IGF + PDGF increases periodontal regeneration - Lynch SE et al 1989 IGF I + BMP 2 act synergistically on OSTERIX - Celil AB et al 2003
  45. 45. Fibroblast Growth Factors • Autocrine / Paracrine regulators of bone formation • Stimulate chemotaxis, proliferation & matrix synthesis of osteoblasts & osteoblast precursor. • Play role in angiogenesis & mesenchymal Cell mitogenesis • Accelerates fractures healing • FGF-2 most potent than FGF-1 - Contrella et al 1988
  46. 46. Bone regeneration GFs IGF FGF VEGF TGF PDGF TNF-alpha , IL-1beta Bone regeneration, remodelling & repair BMPs,Cytokines, GF Mesenchymal cells Differentiation Proliferation
  47. 47. Role of vasculature and neovascularization in tissue engineering • Cell survival… – O2 Supply – Nourishment – Disposal of waste products • Cells more than approximately 200 μm from a blood supply are found to be either metabolically inactive or necrotic. • Tissue implantation volumes < 2–3 mm3
  48. 48. Vasculature = 1) vasculogenesis – denovo formation 2) angiogenesis – mature network Major angiogenic factors – FGF, PDGF and VEGF Blood vessel Angiogenic Sprouting VEGF PDGF,Ang1
  49. 49. Vascular endothelial growth factor • 6 proteins – VEGF A,B,C,D,E and placental GF • Spliced forms like VEGF 121, 165,189 • Primary target is endothelial cells • Also for recruitment , survival and action of osteoblast & osteoclast. • Osteoblasts has VEGF receptors & also secretes VEGF • Mediates other GFs
  50. 50. Vascular endothelial growth factor • Mouse model ; Fracture healing & cortical defect model; - Street J et al 2002 • Major factor coupling osteogenesis + vasculogenesis - Gerber HP et al 2000
  51. 51. Platelet derived growth factor • 3 isoforms ( AA,AB, BB); receptors a & b; • Chemotactic effect on osteoblast & Ct cells - Hughes et al 1991 Increases collagenase transcription & increases IL-6 expression on osteoblasts Indirect effect on Bone resorption - Durant D et al 2000
  52. 52. Platelet derived growth factor • PDGF +βTricalcium phosphate GEM21S rh PDGF + freeze dried bone allograft Excellent results in intrabony defect - Nevins M et al 2007
  53. 53. Applications
  54. 54. •Cell therapy
  55. 55. Gene therapy “Gene therapy is the insertion of genes into an individual's cells and tissues to treat a disease, and hereditary diseases in particular”. Typically aims to supplement a defective mutant allele with a functional one.
  56. 56. • Transformation of .. • Somatic cells • Germ line cells (Sperm, Ova & stem Cells) ex vivo (where cells are modified outside the body and then transplanted back in again) in vivo (where genes are changed in cells still in the body.)
  57. 57. In Periodontics..... A field of biomedicine. • Not applied with success in periodontics – Gene therapy Technology … far from Perfect – Periodontal disease …. Multifactorial… – Genetic variations : • multiple genes, • interactions between genes and the environment,
  58. 58. Gene enhanced TE... Delivery of Therapeutic protein-like growth factor. -short life (a few hours). • This is due to proteolytic breakdown and receptor mediated exocytosis and solubility of the delivery vehicle
  59. 59. Studies in periodontal tissue engineering • Sankaranarayanan S et al 2013, in a 23-year female patient with advanced periodontitis correlated with radiographic evidence of severe horizontal bone loss extending up to the apex of mandibular incisors; after debridement, the defect was implanted with Autologous Bone Marrow Mononuclear Cells impregnated in Thermo responsive Gelatin Polymer. In 6mo, PPD reduced to 2mm from 6mm & CAL 7mm from 13mm. At 36mo radiographic evidence in improvement of vertical n horizontal height.
  60. 60. Studies in periodontal tissue engineering – Reviewed by Elena A. Trofin et al 2013 • 7 case reports (for a total of 22 patients) where MSCs had been applied clinically for infra-bony defects and furcation involvement after chronic periodontitis in humans. • The efficacy of human periodontal cell therapy by grafting autologous stromal cells from gingiva or periodontal ligament with a hydroxyapatite (HA) carrier has been assessed since 1992 (Feng and Hou, 1992; Feng et al., 1995, 2010; Hou et al., 2003).
  61. 61. Studies in periodontal tissue engineering – Reviewed by Elena A. Trofin et al 2013 • Cultured mandibular periosteum-derived cell sheets with PRP have also been used in the treatment of chronic periodontitis without (Mizuno et al., 2010) or with HA in patients suffering from advanced chronic periodontitis (Okuda et al., 2009). • A BMSC-PRP gel has also been used in an infrabony periodontal defect and led to a 4 mm clinical attachment gain (Yamada et al., 2006). These data suggest MSCs may induce efficient and safe periodontal regeneration in humans.
  62. 62. Future directions in periodontics... 1. Gene Therapeutics-Periodontal Vaccination 2. Genetic Approach to Biofilm Antibiotic Resistance 3. An In vivo Gene Transfer by Electroporation for Alveolar Remodeling. 4. Tight Adherence Gene for the Control of Periodontal Disease Progression. 5. Antimicrobial Gene Therapy to Control Disease Progression 6. Gene Therapy to Grow New Teeth Tooth grown with urine stem cells by a team from the Guangzhou Institutes of Biomedicine and Health- Cia et al
  63. 63. Cell sheet engineering – Okano et al 1993 • Temperature responsive culture dishes • At 37 degree celsius ; adhere & proliferate • Below 32 degree celsius cells detach • Allows non-invasive harvest of cultured cells as an intact monolayer cell sheet including deposited ECM • Enables direct transplantation • 3D constructs such as thick cardiac muscle.
  64. 64. Cell sheet engineering
  65. 65. Artificial salivary gland Baum BJ et al
  66. 66. Tissue engineering for dental implants – Biomimetic materials Biomimetic Ca-P coatings Both the superior mechanical properties of titanium and its alloys and excellent biocompatibility of Ca-P materials. Techniques Radiofrequency magnetron sputtering Pulsed-laser deposition Ion-beam sputtering Ion-beam-assisted deposition Electrophoretic techniques Biomimetic Technique Growing a Ca-P thin layer on metals or other implant materials from a physiologically related supersaturated calcifying solution
  67. 67. Benefits Of The Biomimetic Approach Over Plasma- sprayed Hydroxyapatite…
  68. 68. Albumin Plasma protein and plays a fundamental role in the transport of other proteins and functional molecules in the blood. Co-precipitated into the Ca-P coating KRAGH ET AL, 1990 As albumin can bind a wide diversity of ligands reversibly, with high affinity, and albumin microspheres have been used as drug carriers
  69. 69. BMP’s rhBMP-2 incorporated into Ca-P coatings Combination of biomimetic Ca-P coatings and osteoinductive agents can provide superior inductive capability.
  70. 70. Bisposphonates Incorporated into Ca – P coatings • Osteoclast inhibition • Reduced bone turnover • Increased bone mass • Improved mineralization.
  71. 71. • To Master the art of recreating functional viable tissues in the laboratory…..translate the knowledge ….to population at large Promise is GREAT…but challenges exist • Cost efficient… • Availability • Trained staff requirement • Ethical issues
  72. 72. Smile if you think science is real .....

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