How Does Scaffold Porosity Conduct Bone Tissue Regeneration?

Abstract

Despite progresses in tissue healing, repairing large bone defects remains an unmet challenge. Tissue engineering (TE) using porous scaffolds offers great promise in providing solutions by which bone healing can be increased, and the need for further surgical intervention can be reduced. Nonetheless, the successful performance of a porous scaffold depends on key structural factors including porosity, pore size, geometry, and interconnectivity. Herein, recent advancements on this topic are reviewed and the effects of fabrication methods on making potential scaffolds for advanced bone regeneration are discussed.The upward trend of population aging, increased numbers of accidents, sport injuries, trauma, and bone tumor resection are increasing the demand for substitutes to regenerate and/or repair damaged skeletal and dental bones. [1] Bone tissue poses a simple yet highly organized ultracomposition in which each portion plays a pivotal role in moderating the elasticity and strength of the bone. [2] The intrinsically dynamic bone tissue structure allows the restoration of damaged parts via the self-healing process. [3] This remodeling process is dependent on the dynamic equilibrium between the bone-forming (osteoblast) and bone-resorbing cells (osteoclast) during mechanical stimulation. [4] Nevertheless, this healing process is not sufficient for repairing massive and critical bone defects; thus, there is a need for drastic healing accelerators and substitutive or supportive therapeutics. [5] Specially, the regenerating of large bone defects is a serious and challenging clinical issue. To address the issue, different types of bone graft substitutes such as autografts, allografts, and xenografts are used. [6] These grafts, however, come with certain drawbacks, including donor site morbidity and limited supply. Moreover, aged persons cannot provide rich bone tissue for their own tissue replacement due to osteoporosis. [7] To address the limitations associated with natural bone-derived substitutes, biomaterials have been developed during recent decades. [8] Engineering biomaterials made it possible to simulate the bone microenvironment and construct programmable scaffolds for purposeful therapeutic procedures. Bioactive ceramic materials are favorable for bone tissue engineering (BTE) due to their resemblance to the mineral phase of bone, and direct bonding with host bone tissue without the formation of fibrous tissue. In addition, the variety in the chemical composition of bioceramics, particularly silicate-based ceramics (SiCa), can contribute to adjustments in mechanical properties, bioactivity, and biodegradability.A fundamental constituent of engineering tissue is the scaffold, which acts as the structural template providing a suitable substrate for cell proliferation, differentiation, and attachment resulting in new tissue formation. In tissue engineering (TE), the scaffold serves as the structural guide and the substrate for cell anchorage. The scaffold also contributes to the remodeling of the extracellular mat...

Design, Manufacturing and Functions of Pore-Structured Materials: From Biomimetics to Artificial

“…Some researches identify that the macropores at 20–100 μm are used for nutriment and oxygen transfer and adsorption to enhance biomineralized activity, and the others at 100–300 μm serve as rich active sites for bone growth, vascularization, and cell proliferation [ 69 , 78 , 79 ]. Especially, biomimetic mineralization adjusts the porosity of the scaffold to meet the requirements of different bone tissues [ 80 ]. For example, by regulating the calcium-phosphorus ratio close to bone composition, the porosity of composite scaffold was up to 70%, and its Young’s modulus increased from 1.19 MPa by 11.62 MPa; that resembles bone [ 81 ].…”

Recent advances on bioactive baghdadite ceramic for bone tissue engineering applications: 20 years of research and innovation (a review)

“…Since natural bone includes a porous structure with internal voids known as pores, the design of porous ceramic scaffolds is considered one of the most critical implants for tissue engineering applications [ 62 , 63 ]. The high surface area of scaffolds allows them to interact with cells and the surrounding tissue.…”

“…Therefore, considering the spacer size and amount can balance the properties of the yield product. For instance, fabricating a baghdadite scaffold using NaCl as a spacer leads to different porosities and compressive strengths in each sample [ 62 ]. In the freeze-drying method, the baghdadite scaffold is formed by freezing directly.…”

“…In the freeze-drying method, the baghdadite scaffold is formed by freezing directly. Ice crystals form columnar porous structures instead of sacrificial polymer foam [ 62 ]. Sublimation and temperature combine to form oriented ice crystals.…”

Bioceramics in the CaMgSi2O6–Li2O System: A Glass‐Ceramic Strategy for Excellent Mechanical Strength and Enhanced Bioactivity by Spontaneous Elemental Redistribution

“…Due to the various attractive attributes of calcium magnesium silicates as effective bioceramics, such materials from various silicate families have been selected as bone‐tissue engineering materials, including the sorosilicate akermanite (Ca 2 MgSi 2 O 7 ), [ 24,25 ] orthosilicate monticellite (CaMgSiO 4 ), [ 26,27 ] and the pyroxene diopside (CaMgSi 2 O 6 ). [ 28–30 ] Among all the materials, diopside has superior mechanical properties, [ 31 ] and also possesses good cytocompatibility and surface apatite precipitation ability. [ 32,33 ] Consequently, diopside (CaMgSi 2 O 6 ) was chosen as the primary bioceramic material in the present study.…”