Struktur sel:1. Intraseluler2. Extraseluler: Jaringan ikat: Glycosaminoglycans, collagen, Reticular fibers, elastic fibers (Dikeluarkan oleh cartilage dan tulang)

Fungsi kolagen pada jaringan:Collagens contribute to the entrapment, local storage and delivery of growth factors and cytokines and therefore play important roles during organ develop- ment, wound healing and tissue repair. The most abundant proteins in the extracellularmatrix are members of the collagen family. Collagenswere once considered to be a group of proteinswith a characteristic molecular structure with theirfibrillar structures contributing to the extracellularscaffolding. Thus, collagens are the major structuralelement of all connective tissues and are also foundin the interstitial tissue of virtually all parenchymalorgans, where they contribute to the stability oftissues and organs and maintain their structuralintegrity. (Gelse)

Kriteria Scaffold: Q.ChenBone tissue engineering seeks to restore and maintain the function of human bone tissues usingthe combination of cell biology, materials science and engineering principles. The three mainingredients for tissue engineering are therefore, harvested cells, recombinant signallingmolecules, and 3D matrices. Cells and signalling molecules such as growth factors are seededinto highly porous biodegradable scaffolds, cultured in vitro, and subsequently the scaffolds areimplanted into bone defects to induce and direct the growth of new bone. Signalling moleculescan be coated onto the scaffolds or directly incorporated into them. Hence, the first and foremostfunction of a scaffold is its role as the substratum that allows cells to attach, proliferate,differentiate (i.e., transform from a non-specific or primitive state into cells exhibiting the bonespecificfunctions), and organize into normal, healthy bone as the scaffold degrades.

Design criteria for bone tissue engineering scaffolds (1, 4, 10, 11).1. Ability to deliver cellsThe material should not only be biocompatible (i.e. harmless), but also foster cellattachment, differentiation, and proliferation.2. OsteoconductivityIt would be best if the material encourages osteoconduction with host bone.Osteoconductivity does not only eliminate the formation of fibrous tissueencapsulation but it also brings about a strong bond between the scaffold and hostbone.3. BiodegradabilityThe composition of the material, combined with the porous structure of thescaffold, should lead biodegradation in vivo at rates appropriate to tissueregeneration.4. Mechanical propertiesThe mechanical strength of the scaffold, which is determined by both the propertiesof the biomaterial and the porous structure, should be sufficient to providemechanical stability to constructs in load bearing sites prior to synthesis of newextracellular matrix by cells.5. Porous structureThe scaffold should have an interconnected porous structure with porosity > 90%and diameters between 300-500 m for cell penetration, tissue ingrowth andvascularisation, and nutrient delivery.6. FabricationThe material should possess desired fabrication capability, e.g., being readilyproduced into irregular shapes of scaffolds that match the defects in bone ofindividual patients.7. Commercialisation potentialThe synthesis of the material and fabrication of the scaffold should be suitable forcommercialisation.

Ideally, scaffoldsfor tissue engineering should meet several design criteria:(1) the surface should permit cell adhesion, promote cellgrowth, and allow the retention of differentiated cellfunctions; (2) the scaffolds should be biocompatible,neither the polymer nor its degradation by-productsshould provoke inflammation or toxicity in vivo; (3) thescaffold should be biodegradable and eventually eliminated;(4) the porosity should be high enough to providesufficient space for cell adhesion, extracellular matrixregeneration, and minimal diffusional constraints duringculture, and the pore structure should allow even spatialcell distribution throughout the scaffold to facilitatehomogeneous tissue formation; (5) the material should bereproducibly processable into three-dimensional structure,and mechanically strong. (Guoping Chen)

Tissue engineering (TE), an important emerging topic in biomedical engineering, has shown tremendous promise in creating biological alternatives for harvested tissues, implants, and prostheses.7 The underlying concept of tissue engineering is the belief that cells can be isolated from a patient, and its population thenexpanded in a cell culture and seeded onto a carrier. The resulting tissue engineering construct is then grafted back into the same patient to function as the introduced replacement tissue. In this approach, a highly porousartificial extracellular matrix,8 or scaffold, is thought to be needed to accommodate mammalian cells and guide their growth and tissues regeneration in three dimensions. The creation of tissues for medical use is already used to a significant extend in hospitals. These groundbreaking applications involve fabricated skin,9 liver,10,11 pancreas, intestines, urothelium, esophagus,12 nerves,13 valve leaflet,14 cartilage,15 bone,1619 ligament, and tendonSHOUFENG YANG

Bone-Tissue EngineeringThe current standard for the treatmentof bone defects of a critical size that do notheal on their own is an autologous graft.However, the supply of suitable donorbone is limited and harvesting this bonesubjects the patient to additional traumaand risk. The emerging field of bone engineeringattempts to replace or augmentthe current approaches by using porousscaffolds that are designed to support themigration, proliferation, and differentiationof osteoprogenitor cells and aid inthe organization of these cells in three dimensions.These scaffolds may be madefrom a wide variety of both natural andsynthetic materials. Aside from autograftsand allografts of cancellous and corticalbone,14 naturally derived materials includecornstarch-based polymers,5 chitosan (apolysaccharide derived from chitin, foundin crab shells),6,7 collagen,8 and coral.9,10 Ofthese materials, coral has proven to be aneffective clinical alternative to autogenicand allogenic bone grafts for certain applications.11,12(Jeffrey)