Trevor Alleyne Thorpe: His academic life and scientific legacy

Left to right: Prakash P. Kumar; Stephen F. Chandler; Indra S. Harry; Chin-yi Lu; Claudio Stasolla; Edward C. Yeung. Pictured below: Dr. Trevor Alleyne Thorpe 

This special review commemorates the life and contributions of Dr. Trevor Alleyne Thorpe.   Trevor contributed to and trained an impressive number of scientists during his 30-year academic career at the Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada. He was a pioneering scientist who played leading roles in the International Association for Plant Tissue Culture (IAPTC, now known as the International Association for Plant Biotechnology or IAPB) and SIVB. Also, he was the chair/president of IAPTC (1974 to 1978) and the founding Editor-in-Chief of the journal In Vitro Cellular & Developmental Biology – Plant. His renowned laboratory attracted graduate students and visiting scientists from all over the globe. The 15 PhD students, 14 Master’s students, 25 Postdoctoral Fellows, and many visiting scientists who worked with him collectively identify themselves as members of ‘Team Thorpe.’ His major scientific contributions span a range of plant biotechnology disciplines including plant tissue culture, conifer biotechnology, developmental plant physiology, micropropagation and salinity tolerance. Trevor’s PhD thesis advisor was Professor Toshio Murashige, well known for the Murashige and Skoog medium. Professor Murashige was a student of Professor Folke Karl Skoog (a memorable photograph of them together is included in this article). Trevor lived up to his stellar academic lineage, and built a distinguished research career focused on the physiological aspects of plant morphogenesis using explants cultured in vitro. A snapshot of how his lifelong research contributed to our understanding of organized plant development in vivo and in vitro is provided in this article. 

Prakash P. Kumar, Stephen F. Chandler, Indra S, Harry, Chin-yi Lu, Claudio Stasolla, Edward C. Yeung. Trevor Alleyne Thorpe: His academic life and scientific legacy. In Vitro Cellular & Developmental Biology-Plant 56:728-737, 2020. 

This special review commemorates the life and contributions of Dr. Trevor Alleyne Thorpe.   Trevor contributed to and trained an impressive number of scientists during his 30-year academic career at the Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada. He was a pioneering scientist who played leading roles in the International Association for Plant Tissue Culture (IAPTC, now known as the International Association for Plant Biotechnology or IAPB) and SIVB. Also, he was the chair/president of IAPTC (1974 to 1978) and the founding Editor-in-Chief of the journal In Vitro Cellular & Developmental Biology – Plant. His renowned laboratory attracted graduate students and visiting scientists from all over the globe. The 15 PhD students, 14 Master’s students, 25 Postdoctoral Fellows, and many visiting scientists who worked with him collectively identify themselves as members of ‘Team Thorpe.’ His major scientific contributions span a range of plant biotechnology disciplines including plant tissue culture, conifer biotechnology, developmental plant physiology, micropropagation and salinity tolerance. Trevor’s PhD thesis advisor was Professor Toshio Murashige, well known for the Murashige and Skoog medium. Professor Murashige was a student of Professor Folke Karl Skoog (a memorable photograph of them together is included in this article). Trevor lived up to his stellar academic lineage, and built a distinguished research career focused on the physiological aspects of plant morphogenesis using explants cultured in vitro. A snapshot of how his lifelong research contributed to our understanding of organized plant development in vivo and in vitro is provided in this article. 

Prakash P. Kumar, Stephen F. Chandler, Indra S, Harry, Chin-yi Lu, Claudio Stasolla, Edward C. Yeung. Trevor Alleyne Thorpe: His academic life and scientific legacy. In Vitro Cellular & Developmental Biology-Plant 56:728-737, 2020. 

Production of Norway spruce embryos in a temporary immersion system (ITS)

Current members of the Vegetative propagation lab at Natural Resources Institute Finland (Luke) Savonlinna unit, from left to right: Kaija Porkka, Dr. Jaanika Edesi, Dr. Mikko Tikkinen, Dr. Saila Varis, Dr. Tuija Aronen, Sakari Välimäki, Paula Matikainen, Airi Huttunen.

The availability of good quality seed for Norway spruce in Finland fluctuates because of irregular flowering and pests. Therefore, clonal multiplication of seed embryos by somatic embryogenesis (SE) from elite crossings of the national breeding program is being piloted as a supplementary source of forest regeneration material. This is achieved by extracting an immature zygotic embryo from a seed and inducing pro-embryogenic mass (PEM) growth with plant growth regulators, and proliferation through in vitro tissue culture.  PEM from a large number of genotypes is cryopreserved for testing and production purposes.  PEM is further differentiated into mature cotyledonary embryos in dark on a medium with abscisic acid for 7 to 8 weeks, and cold stored for preferably a month or more. After this embryos are germinated in vitro and transplanted into peat in a greenhouse. Norway spruce SE works well on a laboratory scale, but automation is needed to make the process commercially viable. Temporary immersion system (TIS) bioreactors have been proposed as a means of scaling up the production and reducing manual labor. In TIS bioreactors tissue is placed in a basket and the medium is lifted to nourish it at regular intervals. Increased gas exchange can be provided through forced aeration. We tested commercially available TIS bioreactors (Plantform) for pro-embryogenic mass proliferation and embryo maturation using different immersion and aeration cycles, support pad materials and post-maturation treatments. Production of good-quality embryos was achieved in bioreactors, and their quality improved with post maturation desiccation treatment. However, production in Plantform bioreactors does not match embryo production on semi-solid media in terms of labor reduction or embryo quality. This could potentially be achieved by bioreactors designed specifically for conifer SE. 

Sakari Välimäki, Laura Paavilainen, Mikko Tikkinen, Frida Salonen, Saila Varis, Tuija Aronen. Production of Norway spruce embryos in a temporary immersion system (ITS).  In Vitro Cellular & Developmental Biology-Plant 56:430-439, 2020 

The microfollicle: a model of the human hair follicle for in vitro studies

From left to right: Teresa DiColandrea and Ping Hu (Procter & Gamble), Beren Atac and Flora Kiss (TissUse) 

A strong collaboration between TissUse and The Procter & Gamble Company USA lead to a new study of the human microfollicle (MF) for in vitro applications. Access to complex in vitro models that recapitulate the unique markers and cell-cell interactions of the hair follicle is rather limited. Creation of scalable, affordable, and relevant in vitro systems which can provide predictive screens of cosmetic ingredients and therapeutic actives for hair health would be highly valued. In this study, we explored the features of the microfollicle, a human hair follicle organoid model based on the spatio-temporally defined co-culture of primary cells. The microfollicle provides a 3D differentiation platform for outer root sheath keratinocytes, dermal papilla fibroblasts and melanocytes, via epidermal-mesenchymal-neuroectodermal crosstalk. For assay applications, microfollicle cultures were adapted to 96-well plates suitable for medium-throughput testing up to 21 days, and characterized for their spatial and lineage markers. The gene expression profile of microfollicles was also compared to human clinical biopsy samples in response to the benchmark hair-growth compound, minoxidil. The gene expression changes in microfollicles showed up to 75% overlap with the corresponding gene expression signature observed in the clinical study. The results support the use of the MF as a medium-throughput preclinical tool to investigate hair follicle biology and the regulation of hair health and disease. The MF is easy to handle, cost-efficient, and can be produced in high numbers with longer viability, while still comparable with in vivo studies.  

Beren Ataç , Flora Marta Kiss, Tobias Lam, Beatrix Fauler, Clemens Edler, Ping Hu, Thi Phuong Tao, Marian Jädicke, Isabel Rütschle, Reza P. Azar, Scott Youngquist, Thorsten Mielke, Uwe Marx, Roland Lauster, Gerd Lindner, Teresa DiColandrea. The microfollicle: a model of the human hair follicle for in vitro studies. In Vitro Cellular & Developmental Biology- Animal 56:847-858, 2020. 

A strong collaboration between TissUse and The Procter & Gamble Company USA lead to a new study of the human microfollicle (MF) for in vitro applications. Access to complex in vitro models that recapitulate the unique markers and cell-cell interactions of the hair follicle is rather limited. Creation of scalable, affordable, and relevant in vitro systems which can provide predictive screens of cosmetic ingredients and therapeutic actives for hair health would be highly valued. In this study, we explored the features of the microfollicle, a human hair follicle organoid model based on the spatio-temporally defined co-culture of primary cells. The microfollicle provides a 3D differentiation platform for outer root sheath keratinocytes, dermal papilla fibroblasts and melanocytes, via epidermal-mesenchymal-neuroectodermal crosstalk. For assay applications, microfollicle cultures were adapted to 96-well plates suitable for medium-throughput testing up to 21 days, and characterized for their spatial and lineage markers. The gene expression profile of microfollicles was also compared to human clinical biopsy samples in response to the benchmark hair-growth compound, minoxidil. The gene expression changes in microfollicles showed up to 75% overlap with the corresponding gene expression signature observed in the clinical study. The results support the use of the MF as a medium-throughput preclinical tool to investigate hair follicle biology and the regulation of hair health and disease. The MF is easy to handle, cost-efficient, and can be produced in high numbers with longer viability, while still comparable with in vivo studies.  

Beren Ataç , Flora Marta Kiss, Tobias Lam, Beatrix Fauler, Clemens Edler, Ping Hu, Thi Phuong Tao, Marian Jädicke, Isabel Rütschle, Reza P. Azar, Scott Youngquist, Thorsten Mielke, Uwe Marx, Roland Lauster, Gerd Lindner, Teresa DiColandrea. The microfollicle: a model of the human hair follicle for in vitro studies. In Vitro Cellular & Developmental Biology- Animal. 2020 Dec;56(10):847-858. 

In Vitro Strategies for the Conservation of Indian Medicinal Climbers

Members of Dennis Thomas laboratory at The Central University of Kerala, India  including the authors, Prof. T. Dennis Thomas (in the centre of the front row), and A.V. Deepa (first from the left in the front row). 

The Dennis Thomas lab specializes on tissue culture and focuses on conservation and micropropagation of medicinal plants in India as well as their phyto-pharmacological studies. In this paper we consolidated the in vitro propagation and conservation strategies adapted so far for the conservation of Indian medicinal climbers. India’s biodiversity includes two regions, the Western Ghats and the Eastern Himalayas. According to the Botanical Survey of India, of approximately 18,000 species of angiosperms in India, 8000 of them are medicinal plants and several of them are climbers. The angiosperm families mainly composed of climbers include Cucurbitaceae, Convolvulaceae and Diascoreaceae. Many climbers are medicinally important and used as herbal remedies in traditional systems of Indian medicine, including Ayurveda, Sidha and Unani. Several active phytochemicals from different parts of these plants are isolated and used as medicine either alone or in combination with other compounds. Unfortunately, many of these plants are under the threat of extinction due to habitat depletion and overexploitation and conservation efforts are required to ensure their long-term stability. To overcome these difficulties, in vitro propagation strategies are considered the most feasible techniques to facilitate multiplication and rehabilitation of these plants to its natural habitats. This includes medium-term (1–15 yrs.) conservation strategy such as slow growth cultures, long-term conservation technique of cryopreservation and synthetic seed production for conservation of medicinal climbers with nonviable seeds, dormant seeds or seasonal seed setting. Works are progressing in the Dennis Thomas laboratory on standardizing protocols and resolving the challenges including propagation of recalcitrant species, exudation and contamination in the cultures. 

A.V. Deepa, T. Dennis Thomas. In Vitro Strategies for the Conservation of Indian Medicinal Climbers.  In Vitro Cellular & Developmental Biology-Plant 56:784 – 802, 2020. 

Using decellularized grafted leaves as tissue engineering scaffolds for mammalian cells

Left to right Prof. Tanja Dominko, Ms. Yueqing Wang, and Prof. Pamela J. Weathers from the Department of Biology and Biotechnology at Worcester Polytechnic Institute, Worcester MA, USA. 

To address shortages of tissues for transplantation into patients, we and others have been using plant structures as scaffolds upon which to cultivate tissue-specific mammalian cells, e.g. muscle, lung, and heart. Such a “green” solution provides a more sustainable source of transplant tissue. In addition, using patient’s own cells to generate these tissues would alleviate rejection.  Plant structures have a vascular system that is similar in dimensions and hierarchical branching to that in animals. By removing plant cells from plant structures (“decelling”), e.g. leaves, stems, and roots, their structural architecture (scaffold) remains, including their vascular system. This scaffold, consisting mainly of cellulose, hemicellulose, pectin, and lignin, allows cell attachment and growth. Our earlier proof-of-concept used leaf-based scaffolds and when populated with heart muscle cells, these new tissues demonstrated heart muscle contractions. The aim of our report was to build on that success by doing two things: build a thicker scaffold, and provide it with a vascular flow input (arterial) and output (venous).  Both features were absent in our original leaf-based scaffold study. Tissues contained a single leaf with vascular input only via the leaf petiole (leaf stem). Vascular output followed capillary leakage at the distal portion of the leaf.  By grafting two leaves with their petioles at opposite ends, we doubled the thickness of the scaffold and demonstrated that the flow continued between the two leaves via xylem that formed at the grafted laminar surfaces of the leaves allowing effectively arterial-venous tissue perfusion. To our knowledge, successful grafting of leaves via their laminar surfaces has not been reported, and thus presented a challenge. However, our undergraduate student, Yueqing Wang, cleverly determined that by peeling off the cuticle of each leaf and coating them in the plant hormone auxin, one could induce xylem to form thereby joining the vascular system of the two leaves.  GFP-labeled breast cancer cells were used to demonstrate successful mammalian cell attachment and proliferation. Both Ponceau red dye and red blood cells were shown to follow the flow as anticipated: into one leaf, across the graft and out via the petiole of the second leaf. These results suggest that grafted leaves could provide a cell-compatible vascularized scaffold for engineering tissues for transplantation. 

Yueqing Wang, Tonja Dominko, Pamela J. Weathers. Using decellularized grafted leaves as tissue engineering scaffolds for mammalian cells.  In Vitro Cellular & Developmental Biology-Plant 56:765-774, 2020. 

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