The combinatory effect of scaffold topography and culture condition: an approach to nucleus pulposus tissue engineering

Scaffold topography and culture medium conditions for human wharton's jelly mesenchymal stem cells (hWJ-MSC) are critical components of the approach to nucleus pulposus (NP) tissue engineering.

Aim

To evaluate the silk fibroin (SF) scaffold topography analysis (optimal thickness and pore diameter) and to determine culture medium conditions for the growth and differentiation of hWJ-MSC.

Method

hWJ-MSCs were seeded into different thicknesses and pore size diameters and grown in different concentrations of glucose, platelet rich plasma (PRP) and oxygen. The cell-seeded scaffold was evaluated for cell attachment, growth and differentiation potency.

Results & discussion

The results indicated that SF scaffold with a minimum thickness 3.5 mm and pore diameter of 500 μm with cells cultured under low glucose, 10% PRP and normoxia conditions induced the growth and differentiation of hWJ-MSCs, indicated by the accumulation of glycosaminoglycans content and the presence of type II collagen, as markers of NP-like cells.

Mechanical properties of carbon nanotubes/epoxy nanocomposites: Pre-curing, curing temperature, and cooling rate

The effects of composite fabrication, such as pre-curing, curing temperature, and cooling rate, were studied. In this work, the pre-curing was defined as heat treatment of Multi-Walled Carbon Nanotubes (MWNCTs) with Diglycidyl Ether of Bisphenol A (DGEBA) epoxy resin. Acid purified MWCNTs were characterized by Raman spectroscopy and Fourier Transform Infrared Spectroscopy (FTIR). The pre-curing facilitated bonding between MWCNTs and epoxy via the oxirane ring of DGEBA, which accelerated the curing process of epoxy and increased mechanical properties. The elevated curing temperature on the pre-cured sample further improved the composite’s mechanical properties by increasing interfacial bonding due to cross-linking. The rapid cooling using liquid nitrogen during pre-curing treatment prevented re-agglomeration of MWCNTs, showing smaller agglomerates and improving the mechanical properties. Agglomeration was characterized by scanning electron microscopy, while the bonding between MWCNTs and epoxy was examined by the length of fibre pull-out on the fracture surface. Tensile testing was deployed for mechanical properties characterization. The degree of cure was determined by FTIR and Differential Thermal Analysis (DTA).

Cell penetration and chondrogenic differentiation of human adipose derived stem cells on 3D scaffold

The ability of cells to penetrate the scaffold and differentiate into chondrocyte is important in cartilage engineering. The aim of this research was to evaluate the use of silk fibroin 3D scaffold in facilitating the growth of stem cell and to study the role of L-ascorbic acid and platelet rich plasma (PRP) in proliferation and differentiation genes. Cell penetration and type II collagen content in the silk fibroin scaffold was analyzed by confocal microscopy. Relative expressions of CDH2, CCND1, CTNNB1 and COL2A1 were analyzed by reverse transcription-quantitative PCR (RT-qPCR). The silk fibroin 3D scaffold could facilitate cell penetration. L-ascorbic acid and PRP increased the expression of CDH2 and COL2A1 on the 21st day of treatment while PRP inhibited CTNNB1 and CCND1.

Chondrogenic differentiation of Wharton's Jelly mesenchymal stem cells on silk spidroin-fibroin mix scaffold supplemented with L-ascorbic acid and platelet rich plasma

In this research, hWJ-MSCs were grown on silk scaffolds and induced towards chondrogenesis by supplementation with L-ascorbic acid (LAA) or platelet rich plasma (PRP). Silk scaffolds were fabricated with salt leaching method by mixing silk fibroin (SF) with silk spidroin (SS). The silk fibroin was obtained from Bombyx mori cocoon that had been degummed, and the silk spidroin was obtained from wild-type spider Argiope appensa. The effect of scaffold composition and inducer on cell proliferation was observed through MTT assay. The most optimal treatment then continued to be used to induce hWJ-MSC towards chondrogenic differentiation for 7 and 21 days. Scaffolds characterization showed that the scaffolds produced had 3D structure with interconnected pores, and all were biocompatible with hWJ-MSCs. Scaffold with the addition of 10% SS + 90% SF showed higher compressive strength and better pore interconnectivity in comparison to 100% silk fibroin scaffold. After 48 h, cells seeded on scaffold with spidroin and fibroin mix had flattened morphology in comparison to silk fibroin scaffold which appeared to be more rounded on the scaffold surface. Scaffold with 10% (w/w) of silk spidroin (SS) + 90% (w/w) of silk fibroin (SF) was the most optimal composition for cell proliferation. Immunocytochemistry of integrin β1 and RGD sequence, showed that scaffold with SS 10% provide better cell attachment with the presence of RGD sequence from the spidroin silk which could explain the higher cell proliferation than SF100% scaffold. Based on Alcian Blue staining and Collagen Type II immunocytochemistry (ICC), cells grown on 10% SS + 90% SF scaffold with 10% PRP supplementation were the most optimal to support chondrogenesis of hWJ-MSCs. These results showed that the addition of spidroin silk from A. appensa. had impact on scaffold compressive strength and chondrogenic differentiation of hWJ-MSC and had the potential for further development of bio-based material scaffold in cartilage tissue engineering.

Facile synthesis of battery waste-derived graphene for transparent and conductive film application by an electrochemical exfoliation method

Low defect ratio graphene with promising conductivity and transparency can be obtained from the spent graphite in Zn–C battery waste.

Comparison of human Mesenchymal Stem Cells biocompatibility data growth on gelatin and silk fibroin scaffolds

The data showed how gelatin hydrogel and silk fibroin scaffolds could facilitate the growth of human Mesenchymal Stem Cells (hMSC). Gelatin hydrogel and silk fibroin are biodegradable materials. Gelatin hydrogel already has many uses in the medical field, especially in tissue engineering, but silk fibroin scaffold, which is made from the cocoon of silkworm by salt leaching, its role in facilitating growth of hMSC still needs to be proven. Data was obtained by characterization of hMSC, then growing hMSC on silk fibroin scaffolds with pore sizes of ±500 μm and ±900 μm and on gelatin hydrogel scaffolds as control. Testing was performed by counting cell growth on days 1, 3, 5, 7 and 14 with the MTT cytotoxicity assay protocol. The morphology of hMSC that grew on gelatin and silk fibroin scaffolds was observed with a Scanning Electron Microscope (SEM) on day 3. Characterization of the hMSC showed that it fulfilled the requirements of the International Society for Cellular Therapy (ISCT). The water content of the gelatin hydrogel scaffold was higher than the silk fibroin scaffold. Biocompatibility testing showed that the gelatin hydrogel scaffold could support cell growth until day 7, then decreased on day 14 compared to the silk fibroin scaffold based on absorbance on the MTT cytotoxicity assay, while growth on silk fibroin scaffold with pore size 833 ± 147 μm was consistently higher than on pore size 462 ± 66 μm from day 1 to day 14. Cell binding to the silk fibroin was proven from SEM observation.

Chondrogenic differentiation of adipose-derived mesenchymal stem cells induced by L-ascorbic acid and platelet rich plasma on silk fibroin scaffold

Articular cartilage is an avascular tissue with limited regenerative property. Therefore, a defect or trauma in articular cartilage due to disease or accident can lead to progressive tissue deterioration. Cartilage tissue engineering, by replacing defective cartilage tissue, is a method for repairing such a problem. In this research, three main aspects-cell, biomaterial scaffold, and bioactive factors-that support tissue engineering study were optimized. Adipose-derived mesenchymal stem cells (ADSC) that become cartilage were grown in an optimized growth medium supplemented with either platelet rich plasma (PRP) or L-ascorbic acid (LAA). As the characterization result, the ADSC used in this experiment could be classified as Mesenchymal Stem Cell (MSC) based on multipotency analysis and cell surface marker analysis. The biomaterial scaffold was fabricated from the Bombyx morii cocoon using silk fibroin by salt leaching method and was engineered to form different sizes of pores to provide optimized support for cell adhesion and growth. Biocompatibility and cytotoxicity evaluation was done using MTT assay to optimize silk fibroin concentration and pore size. Characterized ADSC were grown on the optimized scaffold. LAA and PRP were chosen as bioactive factors to induce ADSC differentiation to become chondrocytes. The concentration optimization of LAA and PRP was analyzed by cell proliferation using MTT assay and chondrogenic differentiation by measuring glycosaminoglycan (GAG) using Alcian Blue at 605 nm wavelength. The optimum silk fibroin concentration, pore size, LAA concentration, and PRP concentration were used to grow and differentiate characterized ADSC for 7, 14, and 21 days. The cell morphology on the scaffold was analyzed using a scanning electron microscope (SEM). The result showed that the ADSC could adhere on plastic, express specific cell surface markers (CD73, CD90, and CD105), and could be differentiated into three types of mature cells. The silk fibroin scaffold made from 12% w/v concentration formed a 500 µm pore diameter (SEM analysis), and was shown by MTT assay to be biocompatible and to facilitate cell growth. The optimum concentrations of the bioactive factors LAA and PRP were 50 µg/mL and 10%, respectively. GAG analysis with Alcian Blue staining suggested that PRP induction medium and LAA induction medium on 12% w/v scaffold could effectively promote not only cell adhesion and cell proliferation but also chondrogenic differentiation of ADSC within 21 days of culture. Therefore, this study provides a new approach to articular tissue engineering with a combination of ADSC as cell source, LAA and PRP as bioactive factors, and silk fibroin as a biocompatible and biodegradable scaffold.

PEMBUATAN SERAT NANO KITOSAN TANPA BEADS MELALUI PENAMBAHAN PVA DAN HDA

Serat nano kitosan telah berhasil dibuat melalui penambahan polyvinyl alcohol (PVA), denganpermasalahan pada kadar kitosan diatas 50% berat dengan derajat deasetilasi kitosan di bawah 70%, pembentukanbutiran (beads) masih terjadi sepanjang serat nano kitosan/PVA. Penelitian ini dilakukan untuk membuat serat nanotanpa beads yang berbahan dasar kitosan dengan derajat deasetilasi lebih kecil dari 70%. Pembuatan serat nanokitosan dilakukan melalui penambahan polimer PVA dan surfaktan kationik Hexadecylamine (HDA). Sintesiskitosan dilakukan melalui deasetilasi kitin dari kulit udang windu selama 4 jam. Kajian literatur yang mendalampada pembuatan serat nano kitosan/PVA dilakukan dengan analisis mengenai hubungan antara derajat deasetilasikitosan dengan jumlah PVA yang diperlukan untuk membuat serat nano tanpa beads. Larutan dengan variasi rasiokitosan/PVA/HDA dibuat dan diproses menjadi serat nano kitosan/PVA/HDA melalui proses electrospinning.Karakterisasi serat nano dilakukan untuk menentukan morfologi dan diameter serat nano dengan menggunakanScanning Electron Microscope (SEM). Suatu persamaan untuk menentukan kadar PVA yang diperlukan dalammembuat serat nano kitosan/PVA tanpa beads telah diperoleh. Namun, penambahan PVA saja tidak akan efektifdalam mengurangi jumlah beads pada serat nano kitosan. Penambahan HDA pada larutan kitosan/PVA efektifmenghilangkan beads serat nano berbahan dasar kitosan (kadar kitosan 60% berat) dengan derajat deasetilasi 65%.Serat nano kitosan tanpa beads dengan derajat deasetilasi 65% dapat dibuat melalui proses electrospinning denganpenambahan PVA sebesar 40% berat larutan dan penambahan HDA 1x10-6 mol/L.