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Tissue Engineering for Tracheal Replacement: Strategies and Challenges

Samat AA, Hamid ZAA, Mariatti Jaafar @ Mustapha, Yahaya BH

Adv Exp Med Biol, 2022 Apr 08.
PMID: 35389199 DOI: 10.1007/5584_2022_707

The critical feature in trachea replacement is to provide a hollow cylindrical framework that is laterally stable and longitudinally flexible, facilitating cartilage and epithelial tissue formation. Despite advanced techniques and sources of materials used, most inherent challenges are related to the complexity of its anatomy. Limited blood supply leads to insufficient regenerative capacity for cartilage and epithelium. Natural and synthetic scaffolds, different types of cells, and growth factors are part of tissue engineering approaches with varying outcomes. Pre-vascularization remains one of the crucial factors to expedite the regenerative process in tracheal reconstruction. This review discusses the challenges and strategies used in tracheal tissue engineering, focusing on scaffold implantation in clinical and preclinical studies conducted in recent decades.
Scaffolds for Cartilage Regeneration: To Use or Not to Use?

Sha'ban M, Ahmad Radzi MA

Adv Exp Med Biol, 2020;1249:97-114.
PMID: 32602093 DOI: 10.1007/978-981-15-3258-0_7

Joint cartilage has been a significant focus on the field of tissue engineering and regenerative medicine (TERM) since its inception in the 1980s. Represented by only one cell type, cartilage has been a simple tissue that is thought to be straightforward to deal with. After three decades, engineering cartilage has proven to be anything but easy. With the demographic shift in the distribution of world population towards ageing, it is expected that there is a growing need for more effective options for joint restoration and repair. Despite the increasing understanding of the factors governing cartilage development, there is still a lot to do to bridge the gap from bench to bedside. Dedicated methods to regenerate reliable articular cartilage that would be equivalent to the original tissue are still lacking. The use of cells, scaffolds and signalling factors has always been central to the TERM. However, without denying the importance of cells and signalling factors, the question posed in this chapter is whether the answer would come from the methods to use or not to use scaffold for cartilage TERM. This paper presents some efforts in TERM area and proposes a solution that will transpire from the ongoing attempts to understand certain aspects of cartilage development, degeneration and regeneration. While an ideal formulation for cartilage regeneration has yet to be resolved, it is felt that scaffold is still needed for cartilage TERM for years to come.
The Rapid Development of Airway Organoids: A Direct Culture Strategy

Shaffi SC, Zakaria N, Halim NSSA, Ishtiah AA, Patar AA, Yahaya BH

Adv Exp Med Biol, 2023 Mar 30.
PMID: 36991294 DOI: 10.1007/5584_2023_767

INTRODUCTION: The lung is a complex organ composed of numerous cell types. Exposure to air pollutants, cigarette smoke, bacteria, viruses, and many others may cause injury to the epithelial cells that line the conducting airways and alveoli. Organoids are the 3D self-organising structures grown from stem cells and generated from adult stem and progenitor cells. Lung organoids are fascinating tools to investigate human lung development in vitro. The objective of this study was to establish a rapid method for generating lung organoids with a direct culture strategy.
METHODS: Trachea and lung organoids were derived from mixed cell populations of mice primary airway epithelial cells, fibroblasts, and lung microvascular endothelial cells and directly digested from the whole cell population in the distal lung.
RESULTS: The formation of spheres appeared as early as 3 days and continued to proliferate until day 5. The generation of trachea and lung organoids self-organised into discrete epithelial structures was formed within less than 10 days.
CONCLUSION: We conclude that researchers will be able to examine cellular involvement during organ formation and molecular networks because organoids come in a variety of morphologies and stages of development, and this organoid protocol may be used for modelling lung diseases as a platform for therapeutic purposes and suitable for personalised medicine for respiratory diseases.
Functional Analysis of Circular RNAs

Shanmugapriya, Huda HA, Vijayarathna S, Oon CE, Chen Y, Kanwar JR, et al.

Adv Exp Med Biol, 2018 9 28;1087:95-105.
PMID: 30259360 DOI: 10.1007/978-981-13-1426-1_8

Circular RNAs characterize a class of widespread and diverse endogenous RNAs which are non-coding RNAs that are made by back-splicing events and have covalently closed loops with no polyadenylated tails. Various indications specify that circular RNAs (circRNAs) are plentiful in the human transcriptome. However, their participation in biological processes remains mostly undescribed. To date thousands of circRNAs have been revealed in organisms ranging from Drosophila melanogaster to Homo sapiens. Functional studies specify that these transcripts control expression of protein-coding linear transcripts and thus encompass a key component of gene expression regulation. This chapter provide a comprehensive overview on functional validation of circRNAs. Furthermore, we discuss the recent modern methodologies for the functional validation of circRNAs such as RNA interference (RNAi) gene silencing assay, luciferase reporter assays, circRNA gain-of-function investigation via overexpression of circular transcript assay, RT-q-PCR quantification, and other latest applicable assays. The methods described in this chapter are demonstrated on the cellular model.
Contribution of kinin system to the antihypertensive action of angiotensin converting enzyme inhibitors

Sharma JN

Adv Exp Med Biol, 1989;247A:197-205.
PMID: 2690588
On the use of collinear and triangle equation for automatic segmentation and boundary detection of cardiac cavity images

Sigit R, Mustafa MM, Hussain A, Maskon O, Nor IF

Adv Exp Med Biol, 2011;696:481-8.
PMID: 21431588 DOI: 10.1007/978-1-4419-7046-6_48

In this chapter, the computational biology of cardiac cavity images is proposed. The method uses collinear and triangle equation algorithms to detect and reconstruct the boundary of the cardiac cavity. The first step involves high boost filter to enhance the high frequency component without affecting the low frequency component. Second, the morphological and thresholding operators are applied to the image to eliminate noise and convert the image into a binary image. Next, the edge detection is performed using the negative Laplacian filter and followed by region filtering. Finally, the collinear and triangle equations are used to detect and reconstruct the more precise cavity boundary. Results obtained have proved that this technique is able to perform better segmentation and detection of the boundary of cardiac cavity from echocardiographic images.
Prospective Advances in Circular RNA Investigation

Sulaiman SA, Abdul Murad NA, Mohamad Hanif EA, Abu N, Jamal R

Adv Exp Med Biol, 2018 9 28;1087:357-370.
PMID: 30259380 DOI: 10.1007/978-981-13-1426-1_28

circRNAs have emerged as one of the key regulators in many cellular mechanisms and pathogenesis of diseases. However, with the limited knowledge and current technologies for circRNA investigations, there are several challenges that need to be addressed for. These include challenges in understanding the regulation of circRNA biogenesis, experimental designs, and sample preparations to characterize the circRNAs in diseases as well as the bioinformatics pipelines and algorithms. In this chapter, we discussed the above challenges and possible strategies to overcome those limitations. We also addressed the differences between the existing applications and technologies to study the circRNAs in diseases. By addressing these challenges, further understanding of circRNAs roles and regulations as well as the discovery of novel circRNAs could be achieved.
Benign Disorders of the Breast in Pregnancy and Lactation

Taib NA, Rahmat K

Adv Exp Med Biol, 2020;1252:43-51.
PMID: 32816261 DOI: 10.1007/978-3-030-41596-9_6

Benign cystic or solid lumps frequently occur in the breasts of young women, and consequently can also be seen during pregnancy and lactation. Simple cysts do not increase the risk of malignancy. The current management is routine follow-up. Complex cysts are thick walled or contain a mass, and should be followed by a US-guided biopsy and then treated similar to any non-gravid, non-lactating patient.Galactoceles can be detected during the last trimester of pregnancy and during or after stopping lactation. Aspiration can be done to confirm the content. Co-existence of galactocele and malignancy is extremely rare, and the key is to follow up until it resolves.Fibroadenoma is the most frequent lesion found during pregnancy and lactation. Management is usually conservative after triple assessment. Surgery is usually not recommended in pregnant and lactating women unless rapid increase in size occurs or there is discordance in the triple assessment.Lactating adenomas are sometimes interpreted as a variant of fibroadenoma . They can naturally disappear at the end of pregnancy or lactation. Management is usually conservative, and an excisional biopsy is only mandated if it is rapidly enlarging or if there is discordance in the triple assessment.Gestational gigantomastia is a rare condition consisting of diffuse severe hypertrophy of both breasts during pregnancy . Mastectomy and reconstruction may rarely be required in such cases.
Recent Advances in the Genetics of Hypertension

Wei LK, Au A, Teh LK, Lye HS

Adv Exp Med Biol, 2017;956:561-581.
PMID: 27957710 DOI: 10.1007/5584_2016_75

Hypertension is a silent killer worldwide, caused by both genetic and environmental factors. Until now, genetic and genomic association studies of hypertension are reporting different degree of association on hypertension. Hence, it is essential to gather all the available information on the reported genetic loci and to determine if any biomarker(s) is/are significantly associated with hypertension. Current review concluded the potential biomarkers for hypertension, with regards to electrolyte and fluid transports, as well as sodium/potassium ions homeostasis, which are supported by the results of case-controls and meta-analyses.
Biobanking of Human Mesenchymal Stem Cells: Future Strategy to Facilitate Clinical Applications

Yong KW, Choi JR, Wan Safwani WK

Adv Exp Med Biol, 2016;951:99-110.
PMID: 27837557

Human mesenchymal stem cells (hMSCs), a type of adult stem cells that hold great potential in clinical applications (e.g., regenerative medicine and cell-based therapy) due to their ability to differentiate into multiple types of specialized cells and secrete soluble factors which can initiate tissue repair and regulate immune response. hMSCs need to be expanded in vitro or cryopreserved to obtain sufficient cell numbers required for clinical applications. However, long-term in vitro culture-expanded hMSCs may raise some biosafety concerns (e.g., chromosomal abnormality and malignant transformation) and compromised functional properties, limiting their use in clinical applications. To avoid those adverse effects, it is essential to cryopreserve hMSCs at early passage and pool them for off-the-shelf use in clinical applications. However, the existing cryopreservation methods for hMSCs have some notable limitations. To address these limitations, several approaches have to be taken in order to produce healthy and efficacious cryopreserved hMSCs for clinical trials, which remains challenging to date. Therefore, a noteworthy amount of resources has been utilized in research in optimization of the cryopreservation methods, development of freezing devices, and formulation of cryopreservation media to ensure that hMSCs maintain their therapeutic characteristics without raising biosafety concerns following cryopreservation. Biobanking of hMSCs would be a crucial strategy to facilitate clinical applications in the future.
Adipose-Derived Mesenchymal Stem Cells Promote Growth and Migration of Lung Adenocarcinoma Cancer Cells

Zakaria N, Yahaya BH

Adv Exp Med Biol, 2020;1292:83-95.
PMID: 31916234 DOI: 10.1007/5584_2019_464

INTRODUCTION: Mesenchymal stem cells (MSCs) have been used in cancer therapy as vehicles to deliver therapeutic materials such as drugs, apoptosis inducers and cytokines due to their ability to migrate and home at the tumour site. Furthermore, MSCs have been genetically engineered to produce anticancer molecules such as TRAIL that can induce apoptosis of cancer cells. However, MSCs' presence in the tumour microenvironment has shown to be involved in promoting tumour growth and progression. Therefore, the roles of MSCs either promoting or suppressing tumorigenesis need to be investigated.
METHODS: Human adipose-derived MSCs (Ad-MSCs) and A549 cells are co-cultured together in indirect co-culture system using Transwell insert. Following co-culture, both cells were analysed in terms of growth rate, migration ability, apoptosis and gene expression for genes involved in migration and stemness characteristics.
RESULTS: The result shows that Ad-MSCs promoted the growth of A549 cells when indirectly co-cultured for 48 and 72 h. Furthermore, Ad-MSCs significantly enhanced the migration rate of A549 cells. The increased in migration rate was in parallel with the significant increase of MMP9. There are no significant changes observed in the expression of TWIST2, CDH2 and CDH1, genes involved in the epithelial-to-mesenchymal transition (EMT). Ad-MSCs also protect A549 cancer cells from undergoing apoptosis and increase the survival of cancer cells.
CONCLUSION: Secretion of soluble factors from Ad-MSCs has been shown to promote the growth and metastatic characteristics of A549 cancer cells. Therefore, the use of Ad-MSCs in cancer therapy needs to be carefully evaluated in the long-term aspect.
Natural Variation in Freezing Tolerance and Cold Acclimation Response in Arabidopsis thaliana and Related Species

Zuther E, Lee YP, Erban A, Kopka J, Hincha DK

Adv Exp Med Biol, 2018 10 6;1081:81-98.
PMID: 30288705 DOI: 10.1007/978-981-13-1244-1_5

During low-temperature exposure, temperate plant species increase their freezing tolerance in a process termed cold acclimation. The molecular mechanisms involved in cold acclimation have been mostly investigated in Arabidopsis thaliana. In addition, other Brassicaceae species related to A. thaliana have been employed in recent years to study plant stress responses on a phylogenetically broader basis and in some cases with extremophile species with a much higher stress tolerance. In this paper, we briefly summarize cold acclimation responses in A. thaliana and current knowledge about cold acclimation in A. thaliana relatives with special emphasis on Eutrema salsugineum and two closely related Thellungiella species. We then present a transcriptomic and metabolomic analysis of cold acclimation in five A. thaliana and two E. salsugineum accessions that differ widely in their freezing tolerance. Differences in the cold responses of the two species are discussed.