3D Bioplotter Research Papers

Displaying all papers by C. Carvalho (11 results)

Valproate release from polycaprolactone implants prepared by 3D-bioplotting

Die Pharmazie - An International Journal of Pharmaceutical Sciences 2011 Volume 66, Number 7, Pages 511-516

In this study we examined the release kinetics of valproate from polycaprolactone (PCL) implants constructed for local antiepileptic therapy. The PCL implants were produced with a novel 3D-Bioplotting technology. Release kinetics were determined by superfusion of these implants. Valproate was measured in the superfusate fractions with high pressure liquid chromatography (HPLC). The HPLC measurements were linear over a concentration range of 10-500 g/mL for valproate and the limit of quantification was found to be 9 g/mL. The HPLC method used is simple, accurate and sensitive. Within the first day, valproate (10%w/w)-PCL implants released already 77% of the maximum possible liberated…

Calvaria bone chamber-A new model for intravital assessment of osseous angiogenesis

Journal of Biomedical Materials Research Part A 2011 Volume 99A, Issue 2, pages 151-157

The faith of tissue engineered bone replacing constructs depends on their early supply with oxygen and nutrients, and thus on a rapid vascularization. Although some models for direct observation of angiogenesis are described, none of them allows the observation of new vessel formation in desmal bone. Therefore, we developed a new chamber model suitable for quantitative in vivo assessment of the vascularization of bone substitutes by intravital fluorescence microscopy. In the parietal calvaria of 32 balb/c mice a critical size defect was set. Porous 3D-poly(L-lactide-co-glycolide) (PLGA)-blocks were inserted into 16 osseous defects (groups 3 and 4) while other 16 osseous…

Comparison of bacterial adhesion and cellular proliferation on newly developed three-dimensional scaffolds manufactured by rapid prototyping technology

Journal of Biomedical Materials Research Part A 2011 Volume 98A, Issue 2, pages 303-311

Scaffolds used in the field of tissue engineering should facilitate the adherence, spreading, and ingrowth of cells as well as prevent microbial adherence. For the first time, this study simultaneously deals with microbial and tissue cell adhesion to rapid prototyping-produced 3D-scaffolds. The cell growth of human osteosarcoma cells (CAL-72) over a time period of 3-11 days were examined on three scaffolds (PLGA, PLLA, PLLA-TCP) and compared to the adhesion of salivary microorganisms and representative germs of the oral flora (Porphyromonas gingivalis, Prevotella nigrescens, Candida albicans, Enterococcus faecalis, Streptococcus mutans, and Streptococcus sanguinis). Scanning electron microscopy (SEM), cell proliferation measurements, and…

Accelerated Angiogenic Host Tissue Response to Poly(L-Lactide-co-Glycolide) Scaffolds by Vitalization with Osteoblast-like Cells

Tissue Engineering Part A 2010 Volume 16, Issue 7

Background: Bone substitutes should ideally promote rapid vascularization, which could be accelerated if these substitutes were vitalized by autologous cells. Although adequate engraftment of porous poly(L-lactide-co-glycolide) (PLGA) scaffolds has been demonstrated in the past, it has not yet been investigated how vascularization is influenced by vitalization or, more precisely, by seeding PLGA scaffolds with osteoblast-like cells (OLCs). For this reason, we conducted an in vivo study to assess host angiogenic and inflammatory responses after the implantation of PLGA scaffolds vitalized with isogeneic OLCs. Materials and Methods: OLCs were seeded on collagen-coated PLGA scaffolds that were implanted into dorsal skinfold chambers…

Bone repair by cell-seeded 3D-bioplotted composite scaffolds made of collagen treated tricalciumphosphate or tricalciumphosphate-chitosan-collagen hydrogel or PLGA in ovine critical-sized calvarial defects

Journal of Biomedical Materials Research Part B: Applied Biomaterials 2010 Volume 93B, Issue 2, Pages 520-530

The aim of this study was to investigate the osteogenic effect of three different cell-seeded 3D-bioplotted scaffolds in a ovine calvarial critical-size defect model. The choice of scaffold-materials was based on their applicability for 3D-bioplotting and respective possibility to produce tailor-made scaffolds for the use in cranio-facial surgery for the replacement of complex shaped boneparts. Scaffold raw-materials are known to be osteoinductive when being cell-seeded [poly(L-lactide-co-glycolide) (PLGA)] or having components with osteoinductive properties as tricalciumphosphate (TCP) or collagen (Col) or chitosan. The scaffold-materials PLGA, TCP/Col, and HYDR (TCP/Col/chitosan) were cell-seeded with osteoblast-like cells whether gained from bone (OLB) or from…

Vascularization and biocompatibility of scaffolds consisting of different calcium phosphate compounds

Journal of Biomedical Materials Research Part A 2008 Volume 86A, Issue 4, Pages 1002-1011

Scaffolds for tissue engineering of bone should mimic bone matrix and promote vascular ingrowth. Whether synthetic hydroxyapatite and acellular dentin, both materials composed from calcium phosphate, fulfill these material properties has not been studied yet. Therefore, we herein studied in vivo the host angiogenic and inflammatory response to these biomaterials. Porous scaffolds of hydroxyapatite and isogeneic acellular dentin were implanted into the dorsal skinfold chamber of balb/c mice. Additional animals received perforated implants of isogeneic calvarial bone displaying pores similar in size and structure to those of both scaffolds. Chambers of animals without implants served as controls. Angiogenesis and neovascularization…

Incorporation of growth factor containing Matrigel promotes vascularization of porous PLGA scaffolds

Journal of Biomedical Materials Research Part A 2008 Volume 85A, Issue 2, Pages 397-407

In tissue engineering, rapid ingrowth of blood vessels into scaffolds is a major prerequisite for the survival of three-dimensional tissue constructs. In the present study, we investigated whether the vascularization of implanted poly-D,L-lactic-co-glycolic acid (PLGA) scaffolds may be accelerated by incorporation of Matrigel. For this purpose, we investigated in the aortic ring assay the proangiogenic properties of growth factor reduced Matrigel (GFRM) and growth factor containing Matrigel (GFCM), which were then incorporated into the pores of PLGA scaffolds. Subsequently, we analyzed vascularization, biocompatibility, and incorporation of these scaffolds during 14 days after implantation into dorsal skinfold chambers of balb/c mice…

Improvement of Vascularization of PLGA Scaffolds by Inosculation of In Situ-Preformed Functional Blood Vessels With the Host Microvasculature

Annals of Surgery 2008 Volume 248 - Issue 6 - Pages 939-948

Objective: We analyzed, in vivo, whether the establishment of blood supply to implanted scaffolds can be accelerated by inosculation of an in situ-preformed microvascular network with the host microvasculature. Background: A rapid vascularization is crucial for the survival of scaffold-based transplanted tissue constructs. Methods: Poly-lactic-glycolic acid scaffolds were implanted into the flank of balb/c or green fluorescent protein (GFP)-transgenic mice for 20 days to create in situ a new microvascular network within the scaffolds. The prevascularized scaffolds were then transferred into the dorsal skinfold chamber of isogeneic recipient mice. Nonvascularized poly-lactic-glycolic acid scaffolds served as controls. Vascularization, blood perfusion, and…

Bacterial and Candida albicans adhesion on rapid prototyping-produced 3D-scaffolds manufactured as bone replacement materials

Journal of Biomedical Materials Research Part A 2008 Volume 87A, Issue 4, pages 933-943

Rapid prototyping (RP)-produced scaffolds aregaining increasing importance in scaffold-guided tissueengineering. Microbial adhesion on the surface of replacement materials has a strong influence on healing and long-term outcome. Consequently, it is important to examine the adherence of microorganisms on RP-produced scaffolds. This research focussed on manufacturing of scaffolds by 3D-bioplotting and examination of their microbial adhesion characteristics. Tricalciumphosphate (TCP), calcium/sodium alginate, and poly(lactide-co-glycolic acid) (PLGA) constructs were produced and used to study the adhesion of dental pathogens. Six oral bacterial strains, one Candida strain and human saliva were used for the adhesion studies. The number of colony forming units (CFU) were…

Angiogenic and inflammatory response to biodegradable scaffolds in dorsal skinfold chambers of mice

Biomaterials 2006 Volume 27, Issue 29, Pages 5027-5038

For tissue engineering, scaffolds should be biocompatible and promote neovascularization. Because little is known on those specific properties, we herein studied in vivo the host angiogenic and inflammatory response after implantation of commonly used scaffold materials. Porous poly(l-lactide-co-glycolide) (PLGA) and collagen–chitosan–hydroxyapatite hydrogel scaffolds were implanted into dorsal skinfold chambers of balb/c mice. Additional animals received cortical bone as an isogeneic, biological implant, while chambers of animals without implants served as controls. Angiogenesis and neovascularization as well as leukocyte–endothelial cell interaction and microvascular permeability were analyzed over 14 day using intravital fluorescence microscopy. PLGA scaffolds showed a slight increase in leukocyte…

Fabrication of soft and hard biocompatible scaffolds using 3D-Bioplotting

Virtual Modelling and Rapid Manufacturing-Advanced Research in Virtual and Rapid Prototyping 2005 London, England: Taylor & Francis Group, 97-102

In Tissue Engineering and bone reconstruction, alongside the choice of materials, the scaffold design is of great importance. Three dimensional structures not only permit the tuning of chemical and mechanical properties, but they can also copy the outer form of the required bone or cartilaginous structures. While new processes that create such 3D scaffolds by means of Rapid Prototyping have been developed, they are still restricted to a limited type of materials. At the Freiburger Materialforschungszentrum, our group has developed a new process called 3D BioplottingTM. Most kinds of polymers and biopolymers can be used for the fabrication of 3D…