The University of Southampton

Author: Catherine Fowler

The Amazing Spider Goat

Posted on by

Can they swing from a thread? No, but they can produce them!

Several years ago, in my GCSE biology class, I first encountered the concept of gene editing and transgenic animals. Since then, I have become very interested in medical devices and biomaterials. Spider goats perfectly combine these topics and pave the way for potentially revolutionary advances in medicine and healthcare.

Spider Goats

Spider goats appear to be completely regular goats at first glance. However, they have a secret superpower: the ability to produce the spider silk protein in their milk!

How are they made?

There are various ways to produce transgenic animals. The way it was originally achieved in spider goats was by taking some skin cells from the goat and inserting the gene from the spider that creates the silk protein into the nucleus. The nucleus could then be removed from the skin cell and put into an egg cell, which was then implanted into a goat. The result is a goat that can produce the protein for spider silk in its milk. [1]

How is the silk extracted?

In an article written by T. Miller [1], she interviews Justin A., who helped create the original herd of these spider goats, and he explains how the silk is extracted from the goat’s milk.

Firstly, the goat’s milk is collected and frozen. Once the milk has thawed, it can be purified. The first step is to remove any fats and then filter out the smaller proteins. The spider silk protein is separated by selective precipitation (separating a solid from a solution [2]) and washed. Once a purified form of the spider silk protein is obtained, it is suspended in water and placed in a microwave. The purified liquid silk protein can be easily manipulated into its desired form.

THE AMAZING SPIDER GOAT (a short comic)

Spider Silk

Its structure and properties

The type of spider silk focused on by most studies is dragline silk. It has some interesting properties, such as having a good balance between strength and elasticity to enable the spider to catch flying prey. These unique properties means that it surpasses the majority of all natural and man-made materials [3].

Some of its most beneficial properties [3]:

  • Strong
  • Tough
  • Biocompatible (compatible with living tissue [4])
  • Minimally immunogenic (produces an initial immune response, but there are no long term effects)
  • Exceptional cytocompatibility (has very little effect on the structure and function of tissues it comes into contact with [5])
  • Slow degradation rate

Did you know? Spider silk produced by transgenic silk worms has been found to be 6 times tougher than Kevlar, which is used in bullet proof vests! [6]

These properties are a result of mainly two spidroins (proteins) that comprise the silk: MaSp1 and MaSp2. These proteins have very repetitive amino acid sequences that lead to the formation of specific final structures that give the silk its unique physical properties.[3]

Potential medical uses of spider silk

The use of spider silk in medicine is certainly not a new idea. In fact, it was even used by the ancient Greeks and Romans to promote wound healing [3]!

The possibilities for the biomedical applications of spider silk is what particularly interests me about this topic, since it relates to the majority of the modules I am currently studying. For example, both this module and the Orthopaedic Biomechanics module have covered tissue engineering and spider silk has shown great promise to enhance current solutions in this area [7]:

  • Skin regeneration and wound dressing
    • It has been shown to promote the healing of burns
  • Cartilage and tendon tissue engineering
    • Acts as a good scaffold because it degrades relatively slowly and scaffold shouldn’t degrade faster than the rate of new tissue formation [3]. It is also very biocompatible.
  • Neural tissue engineering
    • Has been proven to aid in nerve regeneration

Spider silk also has desirable properties for use in drug delivery and its high tensile strength and excellent biocompatibility make it a good choice for a suture [7].

Why not just use spiders?

  • The spiders are very territorial, so are difficult to keep [3]
  • The silk needs to be made in large quantities to be useful

Ethical concerns

As much as I see a great potential in the use of spider silk to improve healthcare, I understand that there are ethical concerns surrounding the use of transgenic animals. The procedures the animals go through are invasive (e.g. superovulation and taking tissue samples). It is also felt by some people that altering animals in this way is disrupting the natural order of the universe. Ultimately, it is important we take into account the welfare of animals when doing this type of research.

References

[1] T. Miller, “The Spectacular Spider Goat – Goat Journal,” Goat Journal, Aug. 12, 2021. https://goatjournal.iamcountryside.com/kids-corner/the-spectacular-spider-goats/ (accessed Mar. 23, 2025).

[2] “Selective Precipitation — Overview & Examples,” expii. https://www.expii.com/t/selective-precipitation-overview-examples-8536 (accessed Mar. 24, 2025).

[3] F. Bergmann, S. Stadlmayr, F. Millesi, M. Zeitlinger, A. Naghilou, and C. Radtke, “The properties of native Trichonephila dragline silk and its biomedical applications,” Biomaterials Advances, vol. 140, p. 213089, Sep. 2022, doi: https://doi.org/10.1016/j.bioadv.2022.213089.

[4] Merriam-Webster, “Definition of BIOCOMPATIBILITY,” Merriam-webster.com, 2017. https://www.merriam-webster.com/dictionary/biocompatibility (accessed Mar. 23, 2025).

[5] M. F. Sigot-Luizard and R. Warocquier-Clerout, “In Vitro Cytocompatibility Tests,” Test Procedures for the Blood Compatibility of Biomaterials, pp. 569–594, 1993, doi: https://doi.org/10.1007/978-94-011-1640-4_48.

[6] Bronwyn Thompson, “Bionic silkworms with spider genes spin fibers 6x tougher than Kevlar,” New Atlas, Sep. 21, 2023. https://newatlas.com/materials/silkworms-spider-genes-spin-fibers/ (accessed Mar. 23, 2025).

[7] B. Bakhshandeh, S. S. Nateghi, M. M. Gazani, Z. Dehghani, and F. Mohammadzadeh, “A review on advances in the applications of spider silk in biomedical issues,” International Journal of Biological Macromolecules, vol. 192, pp. 258–271, Dec. 2021, doi: https://doi.org/10.1016/j.ijbiomac.2021.09.201.

Neuroprosthetic Devices

Posted on by

Neuroprosthetic devices make use of the nervous system to enhance their ability to efficiently restore function to a part of the body, usually after an injury has occurred [1]. 

Some examples are [2]: 

  • Cochlear implants 
  • Prosthetic limbs
  • Retinal implants

In this particular post I will concentrate on just these examples, explaining what they are and how they work, along with evaluating their risks and any ethical concerns surrounding their use.

Cochlear implants

What are cochlear implants?

Cochlear implants are devices used to allow someone who is deaf or extremely hard-of-hearing to have a sense of sound. Part of the implant is external and sits just behind the ear and the other part is internal and is placed under the skin [3]. The implant picks up sounds using the external part of the device which are then received by the receiver under the skin. These are then converted into electrical signals which can be used to stimulate the cochlear nerve and therefore be understood as sounds by the brain [4]. 

Figure 1: The cochlear implant. Left: The external part of the implant consisting of the transmitter, microphone and speech processor. Right: The internal part of the implant with the receiver under the skin and the electrode in the cochlear [5].

Risks and ethical concerns with cochlear implants

There are many benefits to this type of device which generally improve the patient’s quality of life. Adults tend to benefit from the implant immediately and could have the ability to understand speech without lip-reading, make telephone calls and even perceive different types of sounds [6].

However, there are also some drawbacks to the implant. It is invasive and requires surgery, which comes with various risks such as damage to the facial nerve, infection and leakage of fluids (cerebrospinal and perilymph) [6]. In addition to the surgical risks, there are also some general risks involved: any hearing that was remaining could be lost, the implant could fail and lifestyle changes will need to be made to prevent damage and interference with the implant [6].

There is also an ethical debate involving the use of cochlear implants in deaf/hard-of-hearing children. There was an interesting discussion I found about this topic in an article by Byrd et al. [7]. The article talked about how some people in the Deaf community are sceptical about the devices and feel that they are not worth the risks involved. Additionally, lots of parents in the Deaf community wish to also bring up their children in the community, so that they can share their language, culture and unique experiences. Because of this, some parents will choose to not put their Deaf children through the surgery. However, it has been shown that it’s beneficial for a child to have the implant before 24 months of age to allow better development of speech and language, so in some cases this has raised questions about whether not giving a child the surgery should be considered neglect.

I think that it’s a very complex situation and each case must be looked at individually to determine what’s best for the child in that particular scenario. I also think it’s important that the parents are well informed about the risks and benefits of cochlear implants so that they are able to make the right decision.

Prosthetic limbs

What are neuroprosthetic limbs?

Neuroprosthetic limbs are replacement limbs that are connected to the nervous system allowing the person to control the prosthesis with their brain. For example, in bionic legs, electrodes measure the nerve activity from the person’s intention to move their leg and then a computer in the neuroprosthetic device uses these signals to move the prosthesis [8].

Issues with neuroprosthetic limbs

Due to the type of data collected to train and use these devices, there needs to be an evaluation of the safety of this data to protect it from hacking [9]. Since AI is often involved with these devices, there is bias involved that should be taken into consideration [9].

In my opinion, although there are still some concerns surrounding the use of these devices, the potential benefits by far outweigh the risks, so more research in this area would be beneficial. And as technology improves, as will AI and the ability to protect data, so these concerns could be eliminated in the future.

Retinal implants

What are retinal implants?

Retinal implants are prosthetic devices that aim to restore some vision to those with vision loss by replacing the role of photoreceptors. They can be epiretinal (on the inner surface of the retina), subretinal (behind the retina) or suprachoroidal (between the choroid and the sclera) and they work by using direct electrical stimulation or by using photodiodes [10].

Figure 2: The structure of the retina showing the placement of epiretinal and subretinal implants [11].

Ethical concerns with retinal implants

In the article by Slattery [12], it is mentioned that from observing the data from clinical trials it is clear that visual accuracy cannot be guaranteed from the use of the implants, which can lead to misinterpretations that may affect a patient’s day-to-day life. In conclusion, this type of implant needs to be further researched to give people more confidence in its abilities.

Bibliography 

[1] B. C. Eapen, D. P. Murphy, and D. X. Cifu, “Neuroprosthetics in amputee and brain injury rehabilitation,” Experimental Neurology, vol. 287, pp. 479–485, Jan. 2017, doi: https://doi.org/10.1016/j.expneurol.2016.08.004. 

[2] D. Infante, “Bionics and Neuroprosthetics: The Future of Functionality with Biomedical Engineering,” News-Medical, Nov. 30, 2023. https://www.news-medical.net/health/Bionics-and-Neuroprosthetics-The-Future-of-Functionality-with-Biomedical-Engineering.aspx (accessed Mar. 09, 2025). 

[3] National Institute on Deafness and Other Communication Disorders, “Cochlear implants,” NIDCD, 2021. https://www.nidcd.nih.gov/health/cochlear-implants (accessed Mar. 10, 2025). 

[4] Mayo Clinic, “Cochlear Implants – Mayo Clinic,” Mayoclinic.org, May 10, 2022. https://www.mayoclinic.org/tests-procedures/cochlear-implants/about/pac-20385021 (accessed Mar. 10, 2025). 

[5]“Cochlear implant in Singapore – Hearing Specialist & Audiologist in Singapore | D&S Audiology,” Dsaudiology.sg, 2022. https://dsaudiology.sg/implantable-devices/ (accessed Mar. 11, 2025).

[6] “Benefits and Risks of Cochlear Implants,” U.S. Food and Drug Administration, Feb. 09, 2021. https://www.fda.gov/medical-devices/cochlear-implants/benefits-and-risks-cochlear-implants (accessed Mar. 11, 2025).

[7] S. Byrd, A. G. Shuman, S. Kileny, and P. R. Kileny, “The right not to hear: The ethics of parental refusal of hearing rehabilitation,” The Laryngoscope, vol. 121, no. 8, pp. 1800–1804, Jul. 2011, doi: https://doi.org/10.1002/lary.21886.

[8] S. Ward, “People can move this bionic leg just by thinking about it,” MIT Technology Review, Jul. 2024. https://www.technologyreview.com/2024/07/01/1094459/bionic-leg-neural-prosthetic/ (accessed Mar. 12, 2025).

[9] Marcello Ienca, G. Valle, and Stanisa Raspopovic, “Clinical trials for implantable neural prostheses: understanding the ethical and technical requirements,” The Lancet Digital Health, Jan. 2025, doi: https://doi.org/10.1016/s2589-7500(24)00222-x.[10]

[10] L. N. Ayton et al., “An update on retinal prostheses,” Clinical Neurophysiology, vol. 131, no. 6, pp. 1383–1398, Jun. 2020, doi: https://doi.org/10.1016/j.clinph.2019.11.029.[12]

[11] “File:Retinal implant eyeimplant small.png – Wikimedia Commons,” Wikimedia.org, Jul. 29, 2012. https://commons.wikimedia.org/wiki/File:Retinal_implant_eyeimplant_small.png (accessed Mar. 12, 2025).

[12] M. Slattery, “The ethical future of bionic vision,” Pursuit, Dec. 05, 2017. https://pursuit.unimelb.edu.au/articles/the-ethical-future-of-bionic-vision (accessed Mar. 12, 2025).