Tissue engineering of high density porous polyethylene implant for three-dimensional reconstruction: an experimental study

Development of a Smart Scaffold for Sequential Cancer Chemotherapy and Tissue Engineering

The fabrication of a dual-functional drug-containing porous polymeric scaffold by layer-by-layer surface modification involving citrate-stabilized gold nanoparticles and cisplatin molecules is being reported. These scaffolds were characterized by electron microscopy and X-ray photoelectron spectroscopy. The capability of the scaffolds to release hydrated cisplatin in a slow and sustained manner over two days is established. Most importantly, the scaffolds turn nontoxic and cell-friendly after drug release, thus allowing the noncancerous fibroblast cells to adhere and proliferate (from 5000 cells to 16,000 cells in 6 days), becoming a potential solution toward an effective drug-carrying scaffold for volume-filling applications. The scaffold-mediated cancer cell killing and fibroblast cell proliferation were confirmed by fluorescence microscopy imaging, flow cytometry, and cell proliferation assays. We surmise that such a dual-purpose (drug-delivery and volume-filler) scaffold could help avoid the multiple surgical interventions needed for tumor surgery and cosmetic corrections. To the best of our knowledge, this is the first example of scaffolds with such a dual functionality which gets manifested in a sequential manner.

Auricular reconstruction with polyethylene implants or silicone prosthesis: A single institution experience

Auricular reconstruction is usually necessary in patients with congenital malformations, after traumatic ear amputations or in cases of neoplastic ear disease. Thirty-nine patients who underwent an auricular reconstruction with either silicon prosthesis (21 patients) or porous polyethylene (18 patients) between 2002 and 2013 were retrospectively analyzed at a tertiary academic institution. A total of 25 male und 14 female patients were included in the study. In all, 43 implants were installed in 39 patients. An implant failure was not observed in any of the examined groups. An operative revision was necessary in 5 patients in the silicon prosthesis group (N = 21) and in 4 patients in the porous polyethylene group (N = 18). The most common side effect in the porous polyethylene group was the formation of retroauricular adhesions in 11.1 % by postoperative scaring, while in the silicone prosthesis group 71.4 % of the patients presented with skin reactions around the titanium implants. Our study shows that both techniques are valuable and should be offered to patients in cases of auricular reconstruction due to the low rate of severe complications and the good functional results of both techniques.

Surface Modification of Polymers for Tissue Engineering Applications: Arginine Acts as a Sticky Protein Equivalent for Viable Cell Accommodation

Hydrophobic polymers, for their favorable mechanical properties, are a popular choice as permanent bioimplants. These materials remain absolutely bioinert for years, but throw up challenges when it comes to fast integration with healthy tissue. Addressing this, herein, we present a surface-modification technique of converting the hydrophobic surface of a polymeric film into a hydrophilic one using a layer-by-layer assembly process involving gold nanoparticles and small molecules like amino acids. These films showed much improved animal cell (murine fibroblast) adherence properties compared to commercially available tissue culture plates. Moreover, arginine-modified films exhibited a nearly equivalent cell viability compared to the films modified with the natural extracellular matrix component fibronectin. The surface hydrophilicity and roughness of our novel film were characterized by contact angle measurement and atomic force microscopy. Cell counting, fluorescence microscopy, cell viability, and collagen estimation assay were employed to demonstrate that our film favored a much improved cell adherence, and accommodation in comparison to the commercially available tissue culture plates.

Evaluation and Management of Exposed High-density Porous Polyethylene Implants

Numerous autogenous and alloplastic materials have been used for restoration of contour deformities of the face. Alloplastic materials have come into use to replace autogeneous bone grafts because bone grafts are associated with donor site morbidity, resorption and difficulty in shaping. Porous high-density polyethylene (HDPPE) is a commercial product which is nonallergenic, nonantigenic, noncarcinogenic and nonresorbable, highly stable and somewhat flexible. It has pores of 125-250 mum which enable tissue ingrowth resulting in firm attachment and integration of the implant to the surrounding tissues. In this study we aimed to evaluate the fate of the exposed implants and proposed a method to manage the exposed medpor implants. Twenty rats were used for this experimental study. Three phases involving the implantation, exposition, and the closure of the implants were held respectively. Closure was performed in two groups: 1) After perforating the exposed implants; 2) Without perforating the exposed implants. No serious complications were seen. Perforated exposed implants when covered with flaps rather than grafts could be covered. Exposed implants were not covered easily as indicated by the previous studies. This study demonstrates that early closure of perforated implants with flaps can give the best clinical results when exposed implants are covered in a short period after exposition so that the ingrown fibrous tissues are still intact. We believe that grafting of the exposed medpor implants cannot be effective either in early or late period. Perforating the exposed implants yield successful results as ingrowth of the tissues are enabled.

Comparison of the biological activities of high-density porous polyethylene implants and oxidized regenerated cellulose-wrapped diced cartilage grafts

The use of alloplastic materials in plastic surgery has become more extensive with advancement of autogenous-tissue reconstruction techniques for the repair of defects, tissue augmentation, and the stabilization of bones. An ideal alloplastic material should be nonallergenic, noncarcinogenic, sterilizable, and easy to shape and should not cause rejection. Alloplastic material used for tissue augmentation should have a low rate of resorption and distortion. High-density porous polyethylene implants (Medpor) have been used widely and successfully for tissue augmentation. The Turkish Delight is a material composed of diced cartilage grafts wrapped in oxidized regenerated cellulose (Surgicel). Its indications are similar to those of the Medpor implant, and an additional donor site is usually not needed. Both materials are used in the same anatomical locations, especially for augmentation. Therefore, the authors evaluated the long-term stability of and suitable anatomical sites for these materials. Medpor implants or Turkish Delights were placed subperiosteally or subfascially in 10 young rabbits, and the resultant changes were evaluated 16 weeks after the operation by macroscopy and histopathology. Changes in projections were measured with an ocular micrometer. Medpor implants were neither resorbed nor distorted when placed subperiosteally or subfascially, and were highly stabilized by the surrounding tissues. Turkish Delight also enabled tissue augmentation, but had a significantly higher rate of resorption compared with the Medpor implant and was loosely bound to the surrounding tissue. The Turkish Delight was less resorbed and better fixed to adjacent tissues when placed subperiosteally than when placed subfascially.

Adhesion and proliferation of rat vascular smooth muscle cells (VSMC) on polyethylene implanted with O+ and C+ ions

Polyethylene was implanted with 30-keV oxygen (PE/O+) or 23-keV carbon ions (PE/C+) at 10(13) to 5 x 10(15) ions cm(-2) doses in order to improve the adhesion of vascular smooth muscle cell (VSMC) to the polymer surface in vitro because of its oxidation and carbon-enrichment. The concentration of -CO- groups in the PE/O+ and PE/C+ samples increased only up to doses of 3 x 10(14) and 10(15) ions cm(-2), respectively, and then declined. At the same time, the concentration of these groups, measured at a dose of 3 x 10(14) ions cm(-2), was higher in PE/O+ than in PE/C+ samples. Similarly, the number of initially-adhering rat VSMC (24 h after seeding) increased only up to a dose of 3 x 10(13) and 10(15) ions cm(-2) on PE/O+ and PE/C+ samples, respectively. In addition, between doses of 10(13) and 10(14) ions cm(-2), this number was about two to three times higher on PE/O+ samples. On the other hand, the surface wettability increased proportionally to the implanted ion dose, especially above a dose of 10(14) ions cm(-2). Thus, the number of initially-adhered cells appeared to be positively correlated with the amount of the oxygen group present at the polymer surface rather than with the surface wettability. The higher cell adhesion was accompanied by adsorption of fluorescent dye-conjugated collagen IV in larger amounts. The highest numbers of initially-adhered cells were usually associated with the lowest rates of subsequent proliferation (measured by the doubling time, BrdU labelling and M