@article {17244, title = {New biodegradable membrane for periodontal tissue engineering}, booktitle = {XX European Congress of Veterinary Dentistry}, year = {2011}, month = {2011-08-02 00:00:00}, abstract = {

INTRODUCTION

Periodontium, the organ which sustain the tooth\  is often affected by periodontal disease, an inflammatory disease which can progresses with bone resorption, cementum necrosis and gingival recession or hyperplasia and ultimately, when untreated, leads to tooth exfoliation[6-7].

Tooth extraction surgery was considered the standard procedure to threat PD[8], meanwhile, other therapies/procedures have been used with the aim of inducing periodontal regeneration, such as: gingival flap techniques[7, 9], scaling and root planning[7], root conditioning with demineralizing agents [5, 7-9], direct injection of enamel matrix derivatives, growth or differentiation factors and platelet rich plasma (PRP)[10-12] to the root surface, {\guillemotleft}in situ{\guillemotright} application of filler materials like autografts, allografts and alloplastic materials (hydroxyapatite-HA and tricalcium phosphate-TCP)[5, 7] and ** guided tissue regeneration ** (GTR).

GTR was proposed [5, 8, 13] to guide selectively the cell proliferation in different compartments, as bone or PDL, being the first technique that avoid some of the major drawbacks reports for the other approaches, namely, the gingival epithelium and connective tissue expansion, ankilosis and radicular resorption phenomenon and the difficulty to avoid the collapse of the periodontal defect[4, 7-8, 14]. Several non-absorbable and absorbable (synthetic or natural) polymers and composite membranes have also be tested in this application.

Recently, Tissue Engineering\ (TE) as emerged as an alternative approach for periodontal regeneration. TE involves the use of a support material where mesenchymal stem cells from adult tissues with multipotential capacity[9, 17] are seeded and cultured in order to obtain hybrid materials which can temporary substitute and induce the regeneration of the target tissue[1, 18].

In this work, we described the development and characterization of a new scaffold composed by two different layers: a starch+poly(e-caprolactone) (SPCL) membrane which is expected to degrade along the formation of cementum and periodontal ligament and act as GTR barrier for epithelium and bone tissue growth, and a fiber mesh made of SPCL functionalized with calcium and silica, two ions that have already proved to have osteoconductive properties, and which is expected to promote the regeneration of the osseous component of periodontium. Currently we are also studying the proliferation and differentiation of adult mesenchymal stem cells obtained from adipose tissue in both surfaces, evaluating their behavior along different culture periods and conditions in order to establish the optimal conditions to obtain a suitable tissue engineered construct a future autologous approach in dogs.

MATERIALS AND METHODS

PRODUCTION OF THE SCAFFOLDS

To produce the membrane, a polymeric solution of SPCL [a 30:70 \% w/w blend of starch with epsilon-poly(caprolactone)] was casted on a mold to obtain a membrane. Fiber mesh was obtained by wet-spinning technique injecting the same solution through a needle into a coagulation bath of calcium silicate. Then, the two components were attached to obtain a single scaffold.

SCAFFOLDS CHARACTERIZATION

The morphology of all the developed materials was analyzed by scanning electron microscopy (SEM).

Fourrier Transmission Infra-red (FTIR) analysis was performed to assess the surface chemical composition of fiber mesh part.

Tensile strength of the double layer scaffold was measured.

Degradation behavior under effect of enzymes present in the dog serum (alpha-amylase and lipase) was evaluated, namely, the weight loss, water uptake, scaffold morphological changes and calcium and silica elemental release to the solution.

RESULTS / FINDINGS

MORPHOLOGICAL CHARACTERIZATION\ 

Scanning electron microscopy revealed roughness in the surface of the membrane obtained using the mold. The microscopic image of the SPCL-CaSi fiber mesh (Figure 1) showed us a rough surface with fibers around 195 {\textmu}m and interconnected.

SURFACE CHEMICAL COMPOSITION CHARACTERIZATION

FTIR analysis of wet-spun fiber mesh with silanol functionalization showed siloxane bonds (Si-O-Si), Si-O and Si-OH.

TENSILE TESTS

Regarding the wet samples, they have less mechanical properties against traction stress comparing to the samples in dry state. However, the last ones demonstrate a significant increase in the elongation capacity.

DEGRADATION BEHAVIOUR

After only one day of enzymatic action the material showed a water uptake (WU) around 60 \%. Then, there was a continuous increase of WU, particularly, in the samples immersed in lipase and α-amylase+lipase.

The loss of weigh was gradual in all enzymatic conditions. Lipase was the enzyme with higher effect under the material.

SEM analysis of the surface of the membranes after enzymatic degradation resulted in modification of the surface topography, diameter of the fibers and roughness increasing.

We observed a higher calcium release from the samples in lipase. Instead of that, the silicium was much more released to solution in samples in PBS and amylase.

DISCUSSION

Regarding surface topography, both aspects of the developed membrane are suitable to cell adhesion and proliferation due to its roughness, porosity and interconnectivity of the fibers. Mechanical properties of this scaffolds, particularly, the resistance against traction forces, are enough to maintain its architectural integrity in the periodontal defect and be able to be sutured to the surround tissue. It was proved that this membrane is suitable to be degraded by two serum enzymes. The functionalization of the fiber mesh with osteoinductive groups was verified, conferring to this membrane the potential to act positively in the regeneration of osseous component of periodontium, avoiding the use of other strategies, namely, the use of filling materials.

At the present moment, biological tests with adipose adult stem cells (Figure 2) is being performed, evaluating the potential to proliferate under the material surface and differentiate to different cellular lineages, in order to provide to this scaffold the possibility to be used in a tissue engineering strategy of periodontal ligament and alveolar bone regeneration.

CONCLUSIONS

Investigation in periodontal tissue engineering is a demanding area of veterinary and human dentistry professionals and the development of new approaches which able the clinical practitioner to reach the maximum efficacy in the regeneration of periodontal damages is mandatory. Contribution of different fields of medical, biological and chemical sciences is vital to better understand the mechanisms of the disease and the therapeutic strategies which can be applied.

}, keywords = {Guided tissue regeneration, Periodontium, Tissue engineering}, author = {Requicha, J. F. and Leonor, I. B. and Albuquerque, C. M. and Gomes, M. E. and Reis, R. L. and Viegas, C. A. A.} }