Bdm Curs Ianuarie Recup 2017 [608948]

4. Fenomene de interfata specifice
biomaterial – tesuturi

Curs 10/19.12.2016

4.1. Fenomene de interfata biomaterial – mediu (intra)ocular
Sir Harold Riley – primul
implant de IOL –
noiembrie 1949 – St
Thomas Hospital –
Londra

IOL – intraocular lens Tipuri de dispozitive:
Lentile intraoculare
 Lentile de contact
 Implanturi intracorneale (inele) Tipuri de materiale:
 Hidrofile
 Hidrofobe

Tipuri de biomateriale
HIDROFOBE :
PMMA nefoldabi l – putin folosit in SUA si Europa, inca utilizat in tari in care se mai realizeaza
manual extracapsular cataract extraction (ECCE) – incidenta mica de PCO; polimer rigid, indice
mare de refractie, incizie mare, complicatii postoperator: afectarea celulelor endoteliale,
aderenta celule inflamatoare

Polisiloxani sintetici – foldabil
poli(dimetil siloxan) si poli(difenilsiloxan), indice mic de refractie, afinitate redusa pentru apa;
nerecomandati la pacienti care au ulei de silicon la substitut vitros
Impiedica opacifierea capsulara posterioara (PCO); Calcifiere la pacienti cu hialoza asteroida

HIDROFILE :
Acrilati hidrofili : combinatii de 2 -hidroxietil methacrilate (HEMA) si 6-hidroxihexil methacrilat
(HEXMA), flexibili in stare hidratata (18–38% apa); rigizi in stare uscata;
IOL hidrofile – materiale heterogene cu continut mare de apa
-Lentile taiate in stare deshidratata si apoi hidratate si pastrate in solutie
-Continut de apa < 38%.
Complicatii:
– opacifiere datorata calcifierii – problema majora a lentileleor acrilice hidrofile
– PCO – mai frecvent dezvoltat la IOL hidrofile acrilice fata de lentilele hidrofobe acrilice sau
siliconice; PCO datorita continutului mare de apa, stimulare a cresterii celulelor epiteliale lens
epithelial cells (LEC). [Expert Rev Ophthalmol . 2013;8(2):141 -149]

Fenomene de interfata:

 Umectabilitatea la interfata
 Complicatii superficiale:
• Pierderea transparentei
•Opacifierea capsulei posterioare si a lentilei (PCO – posterior capsular
opacification) (cataracta secundara)
•Calcifiere superficiala sau sub -superficiala

Opacifieri intralenticulare:
 Degenerare de tip fulg de zapada
 Incluziuni mici de apa in materiale hidrofobe [fenomen numit “stralucire” (“glistening”)]
(de ex. cu Acrysof) ( leziuni mai mici decat Degenerare de tip fulg de zapada)
 Calcifiere
 … PCO = principala complicatie a IOL in chirurgia oftalmologica pediatrica

Ochi cu corectie laser a refractiei (Laser in situ
keratomileusis – LASIK) si implantat cu inele
intracroneale Intacs; crestere de celule epiteliale
vizibila

Original legend:
The photo below is a post -LASIK cornea with epithelial ingrowth
and ectasia . The foreign object located in the perimeter of the
cornea is an implantable plastic insert called INTACS , which was
implanted in an attempt to flatten the ectasia protrusion . The t –
shaped hazy white scar at the 9:00 position is from the incision
which was made to insert the Intacs into the cornea. The milky line
running from 7:00 to 8:00 is epithelial ingrowth . Click image to
enlarge. https://www.lasikcomplications.com/Epithelial_ingro
wth.html
Urma inciziei – cicatrice in forma literei T;
localizare – ora 9:00 PCO – celule epiteliale – linie albicioasa;
localizare – ora 7:00 – 8:00 Inelele INTACS 1) Tipuri de complicatii – Opacifiere a capsulei
posterioare prin crestere de celule epiteliale
– Opacifiere ca urmare a cresterii unor “pete” de
celule epiteliale lenticulare pe capsula
posterioara a lentilei; fibroza calsulara
– fenomen multifactorial diferit de opacifierile
intralenticulare
[Expert Rev Ophthalmol . 2013;8(2): 141-149]
-Cresterea epiteliala depinde de biomaterial si
de reactia inflamatoare
– Suprafatele cu unghi de contact mic impiedica
adsorptia proteinelor (fibronectin a,
vitronectin a, laminin a, hialuronan , colagen) ce
precede formarea de ECM
[Materials 2011, 4, 1927 -1940; doi:10.3390/ma4111927;
Expert Rev Ophthalmol . 2013;8(2):141 -149]

[This photo is the cornea of a patient who had LASIK in 2007. This cornea is extremely dry and irregularly shaped. In
addition, epithelial cells from the outside surface of the cornea penetrated and grew under the LASIK flap. The cells
can be seen as a white line extending from the lower cornea at 5:00 o'clock to 8:00 o'clock. The patient is wearing a
specialty gas permeable scleral lens to protect the traumatized corneal tissue din
https://www.lasikcomplications.com/Epithelial_ingrowth.html ; 18.12.2016]
Topografia corneeana corectata operator (LASIK) cu
fixarea unei lentile permeabile la gaze pentru
protectia corneei traumatizate

Crestere de celule epiteliale ;
localizare ora 5:00 – 8:00
Opacifierea capsulei posterioare – ca urmare a cresterii de celule epiteliale
Solutii pentru reducerea riscului de PCO:
 suprafete hidrofile, netede, tratate superficial pentru respingerea proteinelor si
celulelor
 incarcare / eliberare medicamente [Materials 2011, 4, 1927 -1940; doi:10.3390/ma4111927]

2) Tipuri de complicatii in lentile intraoculare – Opacifiere prin degenerare de tip fulg de
zapada

Lentila opacifiata – vedere chirurgicala

Surgical view of the opacified PMMA
lens, under pupil dilation Source: David F.
Chang, M.D .
[Figure 1 din
http://www.eyeworld.org/article -a-case –
of-late-postoperative -opacification -of-a-
pmma -iol; 18.12.2016]
IOL PMMA – cu opacifiere de
tip “snowflake degeneration” Exemplu: Opacifiere de tip degenerare fulg de zapada –
denumire dat morfologiei leziunilor; incidenta > 10 ani post –
implantare; observata in lentile obtinute prin injectie in
matrita, atribuita degenerarii PMMA la expunere
indelungata la UV

Lentila opacifiata explantata – vedere generala si microscopica

Gross and light microscopic photographs of the explanted PMMA lens from
the patient in this case Source: Mamalis/Werner laboratory, Moran Eye
Center [Figure 2 din http://www.eyeworld.org/article -a-case-of-late-
postoperative -opacification -of-a-pmma -iol; 18.12.2016 ]

Lentila in stare uscata,
explantata datorita opacifierii
optice Lentila hidratata, explantata
datorita opacifierii optice
[Figure 3 din Cataract/IOL complications: Moran CPC reports A case of late postoperative opacification of a PMMA IOL,
http://www.eyeworld.org/article -a-case -of-late-postoperative -opacification -of-a-pmma -iol ; 18.12.2016 ] Degenerarea de tip fulg de zapada in PMMA:
 Aglomerari de PMMA degenerat dupa expunere la UV, acumulate in zona centrala si
semi -periferica (zona periferica este protejata de iris)
 leziuni uscate , insa in mediu hidrofil permit acumularea unei cantitati anormale de apa
 opacifiere si mai intensa (figura de mai jos)

 lentilele moderne – obtinute prin tehnici moderne (de ex. strung de mecanica fina); nu
mai manifesta astfel de probleme legenda figurii Gross photographs of a PMMA lens explanted because of optic opacification , in the dry and hydrated
states Source: Mamalis/Werner laboratory, Moran Eye Center (case of Fernando Trindade , M.D., Brazil )

3) Tipuri de complicatii in lentile intraoculare hidrofile – Opacifiere prin calcifiere superficiala
si intralenticulara

o Depunere de particule anorganice (fosfat de calciu) atat la suprafata cat si in interiorul lentilei
o Reducerea / pierderea transparentei
o Fenomen favorizat de permeabilitatea si hidrofilia biomaterialului

Lentila opacifiata inainte de operatie

The opacified IOL before exchange as seen on slit -lamp
examination.
Lentila explantata (a) comparatie cu una noua (b)

The explanted opacified IOL optic and haptics (a) is
compared to a normal IOL (b).

4) Tipuri de complicatii in lentile intraoculare – Calcifierea lentilei intraoculare la pacienti cu
hialoza asteroida

Hialoza asteroida – degenerescenta a vitrosului manifestata prin prezenta uno r corpusculi
asterioizi ce contin calciu si fosfat (stearat si palmiat de calciu, oxalat de calciu, fosfolipide
complexe)
– Favorizeaza calcifierea lentilelor siliconice, initial pe fata posterioara

Lentila siliconica – Opacifiere optica din prima zi
postoperator
Clinical photograph of an eye implanted with a 3 -piece
silicone lens, exhibiting optic opacification on the first
postoperative day . [Fig 1 din Cataract/IOL
complications: Moran CPC reports A case of early
postoperative opacification of a silicone intraocular
lens, http://www.eyeworld.org/article -a-case -of-early –
ostoperative -opacification -of-a-silicone -intraocular –
lens;18.12.2016] Implant extras dupa 78 zile;
fenomen explicat prin
contaminare chimica preoperator
Lentila calcifiata explantata dupa 78 zile; opacifiere vizibila in
stare hidratata (jumatatea stanga); comparatie cu jumatatea
nehidratata transparenta
Gross photograph of the explanted silicone IOL from the patient
described in this case report. The degree of opacification can be
seen in the hydrated state (left half) and compared to the
transparency evident in the dry state (right half). Source (all):
Liliana Werner, MD, PhD [ fig 2 din din Cataract/IOL
complications: Moran CPC reports A case of early postoperative
opacification of a silicone intraocular lens ,
http://www.eyeworld.org/article -a-case -of-early -ostoperative –
opacification -of-a-silicone -intraocular -lens;18.12.2016]

Metode moderne de prevenire a complicatiilor la interfata biomaterial – mediu
intraocular:

1) Lentile intraoculare ce elibereaza medicamente (drug -eluting IOLs):
•previn infectiile
•previn reactiile nedorite ale ochiului la implant ce conduc la opacifiere
•Rezervor de medicament pentru diverse patologii
[Materials 2011, 4, 1927 -1940; doi:10.3390/ma4111927]

2) Lentile hidrofile grefate cu peptide RGD pentru reconstituirea structurii sandwich
capsul a-LEC-IOL, considerata a preveni formarea PCO (LEC – lens epithelial cells)
[ PLOS ONE, DOI: 10.1371/journal.pone.0114973]

3) Design specific pentru blocarea migrarii celulelor epiteliale; utilizarea marginii
posterioare drepte in locul celei rotunjite

[Oliver Findl , chap 12. Intraocular Lens Materials and Design]

4.2. Fenomene de interfata tesut – biomateriale pentru regenerare
nervoasa
Clasica/standard
•Utilizeaza autogrefe
•Inca “standardul de aur”
•Donorul clasic – nervul sural (poate
repara defecte lungi)
•Probleme: discomfort la recoltare;
postrecoltare si disponibilitate
limitata
Metod avansate
•Conduct nervos sintetic
•Solutie la dezavantajele autogrefei
•Nu necesita recoltare de autogrefa
•Risc de raspuns imun
•Limita defectului: 2 -3 cm

Reprezentare schematica – regenerare nervoasa
1 2
4
6 3
5
Mielinizare
si maturare

biomateriale pentru regenerare nervoasa – Polimeri biodegradabili
PGA
Colagen
Copolimer DL -lactida
– caprolactona
Alcool polivinilic

Aplicare chirurgicala conduct regenerare nervoasa

Solutii avansate pentru regenerare nervoasa

Fenomene de interfata in regenerare nervoasa

Fenomene de interfata in
conduct nervos

4.3. Fenomene de interfata cu grefe vasculare
Caracteristici pentru biomateriale:

Proprietatile biomaterialelor pentru grefe vasculare