Category Archives: Biomedical

Ophthalmologic applications of electrospinning

Introduction

In recent years, electrospinning has aroused much interest in the biomedical field of ophthalmology due to the possibilities it offers for the treatment of various pathologies affecting the eye. Especially with the proliferation of available electrospinning biomaterials.

Electrospinning is a fiber production technique based on the use of powerful electric fields, which are applied to a solution formed by one or more polymers (and alternatively other types of materials as well, including even biological materials) and one or more solvents. This solution, usually contained in a syringe-type container when working at laboratory scale, is pumped through a needle or capillary. In electrospinning, a high voltage is applied to the tip of the needle, so that the accumulation of electrical charges on the surface of the droplet produces an electrical repulsion effect between the particles of the solution, until finally the electrical force overcomes the surface tension of the droplet, stretching it to generate a jet. As the jet moves toward the collector, which is at zero or negative voltage, the solvent evaporates, generating polymer fibers that are eventually deposited onto the collector.

The fibers generated by electrospinning can vary from the nanometer and micrometer range according to the interest of each particular application, which is very interesting for biomedical applications, since the proper selection of the polymer allows the creation of fibrillar structures that resemble the extracellular matrix (ECM) in size and arrangement. It is possible to use different electrospinning biomaterials: biopolymers, bioabsorbable polymers, non-bioabsorbable polymers, etc, as long as they are of biomedical grade.

Electrospinning applications in ophthalmology

Vision is one of the five primary senses of the human being, so any pathology affecting the ocular system has a great impact on people’s quality of life. According to a report by the World Health Organization, at least 2.2 billion people in the world suffer from vision-related pathologies [1]. Of these, it is estimated that almost 1 billion could be preventable or treatable [2].

In this context, fibers generated from electrospinning biomaterials offer a number of advantages in the development of new ocular therapies. Nanofibers offer a very high surface area, which is advantageous for tissue regeneration and controlled drug release applications. In addition, the adjustable porosity of nanofiber matrices favours cell growth and proliferation and does not interfere with tissue respiration and gas exchange.

Main applications of electrospinning in ophthalmology

  1. Controlled drug delivery

Electrospinning is being used to create nanofiber arrays in which drugs and active ingredients are incorporated. The spatial configuration of the nanofibers allows a sustained and controlled release of drugs into the eye in a very efficient manner. The nanofiber matrix is based on appropriately selected electrospinning biomaterials as required by the specific application.

For example, in the treatment of glaucoma, the controlled release of drugs can reduce intraocular pressure for a longer period of time. On the other hand, if the nanofiber matrix is loaded with anti-inflammatory agents, pathologies such as uveitis or post-operative inflammation can be treated more effectively. If antibiotics are used, corneal infections can be treated.

  1. Ocular tissue engineering

Nanofiber arrays generated with electrospinning biomaterials are the ideal support for ocular tissue engineering due to their similarity to the extracellular matrix, thus promoting cell adhesion and proliferation, as well as regeneration of damaged tissues in the eye. These nanofiber matrices can replace damaged corneal tissue, as well as contribute to the regeneration of retinal and optic nerves.

  1. Ocular medical devices

Ocular medical devices, such as intraocular lenses, artificial corneal implants, or even contact lenses, can benefit from the possibility of depositing a thin layer of nanofibers on or around them. In this way, this nanofiber layer will act as an interface between the medical device and the eye, stimulating the growth of cells around the device, thus increasing its biocompatibility and reducing the possibility of rejection. In intraocular devices, this nanofiber interface and subsequent cell proliferation also helps to better fix the implant inside the eye.

Conclusions

Electrospinning is a very versatile technique that has numerous applications in the field of ophthalmology due to its ability to control the characteristics of the nanofibers obtained. These applications are constantly evolving and improving thanks to the new electrospinning biomaterials that are becoming increasingly available. Advances in electrospinning and its applications in ophthalmology will provide researchers and physicians with a powerful tool to improve the quality of life of people with ocular pathologies.

 

References

[1] D. Sakpal et al., “Recent advancements in polymeric nanofibers for ophthalmic drug delivery

and ophthalmic tissue engineering,” in Biomaterials Advances 141 (2022) 213124.

[2] D. Mishra et al., “Ocular application of electrospun materials for drug delivery and cellular

therapies,” in Drug Discovery Today vol. 28, num. 9, 2023.

Electrospun scaffolds for kidney tissue engineering: on the way towards kidney organoids

Chronic kidney disease is one of the deadliest diseases all around the world. Current healing methods mostly rely on transplantation and dialysis. Engineering of kidney tissues in vitro from induced pluripotent stem cells could provide a solution by restoring the function of damaged kidneys. Electrospinning is a technique that has shown promise in the development of physiological microenvironments of several tissues and could be applied in the engineering of kidney tissues as well.

So far several approaches with electrospinning were attempted. Synthetic polymers such as PCL, PLA and PVOH have been explored in the manufacturing of fibers that promote the proliferation and cell-to-cell interactions of kidney cells. Also natural polymers like silk fibroin have been explored alone and in combination with synthetic polymers promoting the differentiation of podocytes and tubular specific cells. Natural polymers are highly interesting but in many cases they do not provide the mechanical resistance required, that is the reason for combining with synthetic polymers which can balance the lack of resistance.

Furthermore, the use of the electrospinning technique in combination with other manufacturing methods such as bioprinting are highly promising aiming to develop more organized, mature and reproducible kidney organoids. It is important to take into account that kidney cells’ behaviour is strongly dictated by the complex 3D microenvironment. Kidney organoids derived from human induced pluripotent stem cells can be attractive 3D models for different purposes, including to model kidney embryonic development, kidney disease, and renal regeneration. The electrospinning technique is also compatible with live cells encapsulating them in the desired environment.

Electrospinning have been demonstrated to be a promising technique to develop kidney tissues in vitro. However it is still a challenge the lack of knowledge in the specific stimulus required to create kidney organoids. In essence, electrospinning for tissue engineering offers significant benefits due to its unique ability to create biomimetic structures. It can fabricate fibrous scaffolds that closely resemble the extracellular matrix of tissues, promoting cell growth and tissue regeneration. Furthermore, electrospinning for tissue engineering applications allows control over fiber diameter and porosity, aiding in the customization of scaffolds. Electrospinning for tissue engineering has shown to be promising in areas like bone, skin, organs and vascular grafts. Its versatility enhances the potential of electrospinning for tissue engineering applications, marking a significant step forward in regenerative medicine.

Further information can be found in the paper written by Claudia C. Miranda, Mariana Ramalho, Mariana Moço, Joaquim Cabral, Federico Castelo Ferreira and Paola Sanjuan-Alberte from Universidade de Lisboa.

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