Design, Preparation and Characterization of 3D ...

Tessuti connettiviMateriali e tecnologie per la realizzazione di scaffolds per l’ingegneria dei tessuti

Osso trabecolareOsso compattoDentinaSmaltocemento Menisco

TendiniLegamentiIVDTMJ disc

MINERALIZZATI

DENSI

•The medial meniscus is somewhatC-shaped and occupies approximately51% to 74% of the medial tibial plateau.•The lateral meniscus is almostO-shaped and occupies approximately75% to 93% of the lateral tibial plateau.

The two major phases of meniscus are:

1) a fluid phase containing water and electrolytes;

2) a solid phase containing collagen (type I), proteoglycans, glycoproteins and chondrocytes.

Tissue Water Collagen ProteoglycansMeniscus 60-70% 55-65% (type I, dry weight) 1-3%

Materiali e tecnologie per la realizzazione di scaffolds per l’ingegneria dei tessuti

Pig meniscus

MENISCO

fibrocartilaginous tissue


Cellular componentsChondrocytes and fibroblasts.

Matrix componentsElastin (0.6% dry weight)Proteoglycans (1-3%)GlycoproteinsCollagen:1) primarily type I (55-65% dry weight), also types II, III, V, VI (5-10%

dry weight);2) the superficial layer consists of a thin layer of randomly oriented fibers;3) the lamellar layer also consists of randomly oriented fibers, but in the

peripheral portions the fibers are oriented radially;4) the deep zone consists of circumferentially oriented fibers with a small

amount of radially oriented fibers.


Functions•Enable the femoral condyles to articulate congruently;•Distribute compressive and shear forces;•Act as “shock absorbers”;•Prevent synovial impingement;•Disperse synovial fluid for lubrication and proper nutrition;•Limit extremes of flexion and extension;•Facilitate complex movements;•Control rotating instability.


A) Rolling;B) Sliding;C) Rolling + sliding.

Menisci movements:a) extension;b) flexion.

Menisci movements:a) External rolling;b) Neutral rolling;c) Inner rolling.


Examples of tearing

Longitudinal tear Horizontal tear

Arthroscopic repairsuturing.


Rigenerazione del MeniscoBlend di PCL/HYAFF (derivati dell’acido ialuronico)

PCL/THF 80/20 miscelato a 45°C

Fase solida

93.9% (w/w) cloruro di sodio (granulometria 315–400 µm)

3.5% (w/w) bicarbonato di sodio (granulometria 140–315 mm)

2.6% (w/w) acido citrico (granulometria inferiore a 200 mm)

Scaffold Materials

Reverse engineering e rapid prototyping del menisco di pecoraStampo

Soluzioni PCL e HYAFF-11p75 HE (PCL/HYAFF 70/30 (w/w) miscelati con la fase di sale (rapporto polimero/salt di 1/10)

Solvent Casting & Salt Leaching

Innovative materials and technologies for a bio-enginneredmeniscus substitute”, FP5


Sheeplateral meniscus

Sheepmedial meniscus

Sheep meniscus section

Lateral and MedialTeflon moulds

LateralMeniscusMIMICS

MedialMeniscusMIMICS

Reverse engeneering del menisco di pecora

3D x-Ray


Lateral meniscus with net

Medial meniscus with oriented fiber

section

section

3D x-Ray imaging

scaffold di menisco basato su PCL


rigenerazione del menisco•Semina e coltura di condrociti articolari di pecora

•Implantaziuone in pecora

Scaffold non seminato Scaffold seminato

Le strutture sono entrambeintegrate

Il follow-up istologico a 4 mesiindica che la deposizione dimatrice cartilaginea avvienesolo negli scaffold seminaticon cellule

Kon et al., Tissue Engineering for Total Meniscal substitution: Animal Study in Sheep Model. Tissue Engineering: Part A 6, 2008,1067-80



Proprietà biomeccaniche del disco intervertebrale naturale e del disco con nucleo polposo artificiale iniettabile, D. Ronca, A. Gloria, R. De Santis, F. Causa, G. Guida, L. Ambrosio, L. Nicolais. Giornale Italiano di Ortopedia e Traumatologia. Vol. XXXII, Suppl. 1, Ottobre 2006.

Both partial and total functional disorders of spine constitute one of the most disabling, common and costly problem of

current surgery.The surgical treatment may involve the partial or total

resection of the Intervertebral Disc (IVD).Thus, implants for vertebral fusion are often required in

order to immobilize the diseased column.

AGEING DEGENERATION



DISCO INTERVERTEBRALE

LEGAMENTO

braidingfilament winding

Filament WindingLAB101

Nucleus pulposus consists of a network of delicate collagenous fibers in mucoprotein gel, rich in polysaccharide (high water content like gel)

Annulus fibrosus makes up peripherical portion of disc structure, composed of fibers running obliquely in layers with crossing angle of 45-60 deg

End–plate contains no fibrillar connection with collagen of subchondral bone of the vertebrae

Microstructure

J. J. Cassidy, A. Hiltner, E. Baer,. J. Mater. Sci.: Mater. in Med. 1 (1990) 69-80.

Visco-elastic propertie of natural IVD

Biomechanics

Ela

stic

mod

ulus

[MPa

]

Cervical Thoracic ThoracicLumbar

Lumbar


…the design is driven using the mimiking approach: learn from nature

MatrixHydrophilic Semi-Interpenetrating Polymer Network:

poly(2-hydroxyethyl-methacrylate) (PHEMA)poly(methyl-methacrylate)PHEMA/PMMA 80/20w/w

ReinforcementPolymers Fiber

Poly(ethylene-terephtalate) PET40% by volumeWinding angle: from 45 to 65 degrees

Filament Winding &Radical polymerization

AIBNEGDMA90°, 2hrs

45°

65°

Hydrogel

Composite Hydrogel

ϑ

L. Ambrosio et al. J. Proc. Instn. Mech. Engrs., 212H, 1998, 93-99


Static properties•J-shaped stress-strain curve•Compressive modulus 80-110 MPa•Maximum stress 12-20 MPa

0

5

10

15

20

25

0 0.1 0.2 0.3 0.4 0.5 0.6

sample 1sample 2sample 3sample 4

Strain [mm/mm] cervical thoracic lumbar

Natural DiscArtificial Disc

Stre

ss [M

Pa]

Tailoring of mechanical properties• Composition of the matrix• Volume concentration of the fibers• Winding angle of the fibers…to obtain IVD Device for a specific spine location


Compression testing inWater environment at 37°C

Methods

Loops around:•Creep fatigue•DMA•Creep recovery

MTS858 Bionix dynamometerLoading cell 25KN

δcos*EE =′

δsin*EE =′′

Storage modulus

Loss modulus

Complex modulus0

0*

εσ

=E

Dynamic-mechanical and fatigue


E′ increases with the increasing mean load level

and with the increasing number of cycles (cyclic

hardening)

Dynamic-mechanical and fatigue

0.102

0.104

0.106

0.108

0.11

0.112

0.114

0.116

0.118

0 5000 1 104 1.5 104 2 104 2.5 104

after 1 cycleafter 10 cyclesafter 1000 cyclesafter 100000 cyclesafter 1000000 cyclesafter 10000000 cycles

Stra

in (m

m/m

m)

Time (sec)

Creep-recovery steps of 8 hours (sleeping time) at

200 N (horizontal position) suggest high mechanical

stability after fatiguing


Dynamic-mechanical properties of a novel composite intervertebral disc prosthesis, A. Gloria, F. Causa, R. De Santis, P.A. Netti and L. Ambrosio. Journal of MaterialsScience: Materials in Medicine. 2007, vol. 18, no11, pp. 2159-2165


Protesi totale biomimetica

•PEI is dissolved in chloroform (15% ww of PEI)•Carbon fibers impregnated with the PEI/Chloroform solution are wound with an angle of ± 45°

•Chloroform is removed under vacuum at 58°C•The composite system is hot pressed (35bar, T=240°C, t=15min)

Composite cages filament winding and hot compression molding technologyComposite cage geometry (di=4mm; de=8mm; L=16mm)


Porcin model

Composite Cages

12 large white-duroc race of 50-55 Kg by weight and 1.9-2.1 months old

Titanium cagesMod. Inter Fix Ti, (Ti6Al4V) D=10mm L=20mmSOFAMOR Danek

Cages

PEI/carbonHA coated


Southerland SR, Remedios AM, McKerrell JG, Litwin D: Laparoscopic approaches to the lumbar vertebrae. An anatomic study using a porcine model. Spine. 1995 Jul 15;20(14):1620-3

Preliminary skills concerning the cage implantation into L4-L5 discs of pig’s carcasses suggested that the posterior-peritoneal approach was the less invasive treatment

A hole is made in the disc using a stainless threaded tool (diameter of 8mm)

The composite device is screwed into the disc using a screwdriver tool whose tip was designed in order to be perfectly inserted in the special groove on the top of the composite cage.


Spine sectioning

Specimen of two half adjacent vertebral body (L4-L5)IVD treatment:Control (8months)Composite (5months)Titanium (10 months)

Pigs were sacrificed at an age of 5, 8 and 10 months (average weight of 110±32 Kg)


Pathological anatomy investigation

diamond saw low speed microtome slicesth=5mm chilled water

Normal-conformed bone tissue is well evident around the

composite cage


L. Manto, R. De Santis, G. Carrillo, G. Ambrosio, L. Ambrosio, L. Nicolais. Novelcomposite intervertebral disc cage for spine fusion. Journal of Bone And Joint Surgery - British Vol 87-B, Issue SUPP_I, 68, 2005


A. Gloria, L. Manto, R. De Santis, L. Ambrosio. Biomechanical behavior of a novel composite intervertebral body fusion device Journal of AppliedBiomaterials & Biomechanics 2008; Vol. 6 no. 3

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