Research and Projects

As a Beckman Scholar through the Arnold and Mable Beckman Foundation, I developed an independent research proposal aimed at investigating regulators of normal collagen crosslinking, which essentially contributes to tendon mechanical properties. This project assess my hypothesis that the underlying collagen structure and collagen crosslinking is unique between energy storing and positional tendons and that mechanical stimuli regulates production of lysyl oxidase (LOX, the primary enzymatic collagen crosslinker in tendon). I developed a fluid shear stress model to mechanically load mouse mesenchymal stem cells (MSCs) and performed Western Blotting to asses the effects of mechanical loading and the Transforming Growth Factor (TGF)-beta2.

Results: 1. TGF-beta2 appears to be a primary driver of LOX activity in MSCs 2. Low magnitudes of fluid shear stress may also govern LOX activity

Impact: LOX regulation is a complex process regulated by a variety of factors, likely including Transforming Growth Factors (TGFs) and mechanical loading. Control of LOX could be used to manipulate collagen scaffold matrix stiffness in future applications.

Publications;

*Ellingson AJ, *Pancheri NM, Schiele NR. Potential Regulators of LOX Production in Tenogenically Differentiating MSCs. In preparation for Annals of Biomedical Engineering.

*denotes shared lead authorship

Presentations:

Pancheri NM, Ellingson AJ, Schiele NR. Investigating regulators of collagen crosslinking enzyme production for tendon formation. Biomedical Engineering Society (BMES) Annual Meeting, October 6-9, 2021. Virtual Oral Presentation.

Pancheri NM, Theodossiou SK, Ellingson AJ, Schiele NR. Potential regulators of tendon development in rat tendons and tenogenically differentiating MSCs. Annual Beckman Symposium, Irvine, CA, August 6-8, 2021. Virtual Poster Presentation.

Images:

Right: Representative cell images for MSCs culture at 3d and 7d

Collagen crosslinking in developing and adult tendons

Above: Review article graphic abstract (Pancheri and Ellingson, 2022)

This project is a co-first author review article summarizing the state-of-the-art on collagen crosslinking (the bonds between the collagen molecules that composed tendon) in developing and adult tendon tissues. This article has two primary focuses 1. enzymatic collagen crosslinking 2. nonenzymatic collagen crosslinking. My primary focus for this manuscript was writing the section on enzymatic crosslinking (with a emphasis on enzymatic collagen crosslinkers, like lysyl oxidase and lysyl hydroxylases), article finalization/submission, and response to reviewers (ongoing).

Results:

Impact: A peer-reviewed review article discussing tendon collagen crosslinking and investigating the knowledge gaps in the field of tendon tissue engineering.

Publications:

*Ellingson AJ, *Pancheri NM, Schiele NR, Collagen Crosslinking in Developing and Adult Tendons. eCells and Materials Journal, April 5, 2022. DOI: 10.22203/eCM.v043a11

*denotes shared lead authorship

LINC complex signaling for tendon mechanosensing

Above: Representative force displacement curve

This is an ongoing project using genetically modified mice (from Boise State University) w/ a LINC (Linker of Nucleoskeleton and Cytoskeleton) Complex KO (a mechanosensing mechanism in cells). I performed mechanic testing of tail and Achilles tendons, used SHG imaging to visualize collagen crimp structure, and helped conduct immunofluorescence imaging.

Results: 1. KO increased Achilles elastic modulus and decreased cross sectional area 2. KO decreased tail maximum stress and increased cross sectional area. 3. No apparent differences in collagen or cellular morphology (preliminary).

Impact: The LINC Complex is necessary for development of normal tendon mechanical properties, but impacts unique tendons different (e.g., energy storing vs positional tendons).

Publications: In preparation (est. Summer 2022)

Relationship between collagen crimp and tendon mechanical development

Above: Representative SHG images of collagen crimp

I used SHG imaging to quantify collagen crimp structure during rat tendon development (P1-20) and performed correlation analyses against various mechanical properties (force, stress, strain, modulus, stiffness, displacement, cross sectional area) of tails and Achilles tendons.

Results: 1. collagen crimp distance increases during development 2. Tail and Achilles tendon collagen crimp is similar during early development, but increases at P20 3. changes in collagen crimp correlate to some mechanical properties (force, strain, stiffness) and in a tissue dependent manner (i.e., tail vs Achilles tendon)

Impact: Maturation of crimp structure may contribute to some mechanical properties (and unique to different tendon types), suggesting other mechanism may be governing mechanical development.

Presentations:

Pancheri NM, Theodossiou SK, Courtright JM, Brumley MR, Schiele NR. Association between collagen crimp and mechanical properties in developing Achilles and tail tendons. National Conference on Undergraduate Research, April 12, 2021. Virtual Poster Presentation.

Pancheri NM, Theodossiou SK, Courtright JM, Brumley MR, Schiele NR. Relationship between collagen crimp and mechanical development in Achilles and tail tendons. Biomedical Engineering Society Annual Meeting, October 14-17, 2020. Virtual Poster Presentation.

Pancheri NM, Theodossiou SK, Courtright JM, Brumley MR, Schiele NR. Association between collagen crimp and mechanical properties in developing tendons. Idaho Conference on Undergraduate Research, July 23-24, 2020. Virtual Poster Presentation.

Altered neonatal locomotion impacts weight-bearing tendon function, but not collagen morphology

Idaho IDeA Network of Biomedical Research Excellence (INBRE) Undergraduate Research Fellow Summer 2019, 2019-2020 Academic Year¹

Through this fellowship, I contributed to significant progress on a project exploring the effects of altered locomotion on neonatal rat Achilles and tail tendons. My role on the project included leading tendon imaging on an Olympus FluoView 1000 Confocal Microscope, running comparative image analysis, and analyzing mechanical testing data from Achilles and tail tendons.

This fellowship concluded with a poster at the Statewide INBRE 2019 Summer Conference where I placed 3rd in the Poster Presentation Competition for Undergraduate Fellows and 3rd overall in the Fast Pitch Science Competition (A competition to present your research in 3 minutes or less).

Results: 1. Altered neonatal locomotion affects tendon (Achilles and tail tendon mechanical properties) 2. Underlying collagen structure remained unaffected 3. Altered neonatal locomotion decreased weightbearing behavior

Impacts: Weight bearing behavior associated with normal tissue development appears to regulate tendon mechanical properties.

Publications:

Theodossiou SK, Pancheri NM, Martes AC, Bozeman AL, Brumley MR, Raveling AR, Courtright JM, Schiele NR. Neonatal spinal cord transection decreases hindlimb weight-bearing and affects formation of rat Achilles and tail tendons. Journal of Biomechanical Eng. 2021,DOI: 10.1115/1.4050031. PMID: 33537729.

Presentations:

Pancheri NM, Theodossiou SK, Bozeman AL, Martes AC, Brumley MR, Schiele NR. Altering neonatal locomotion impacts tendon function, but not collagen morphology. Biomedical Engineering Society Annual Meeting, Philadelphia, PA, October 16-19, 2019. Poster Presentation.

Theodossiou SK, Pancheri NM, Courtright JM, Bozeman AL, Brumley MR, Schiele NR. Postnatal Energy-Storing and Positional Tendon Development Shows Distinct Levels of Mechanotransducers. International Symposium on Ligaments and Tendons (ISL&T) XVIII, Phoenix, AZ, February 7, 2020. Podium Presentation.

Theodossiou SK, Pancheri NM, Bozeman AL, Martes AC, Brumley MR, Raveling AR, Schiele NR. Spinal cord transection disrupts neonatal locomotion and tendon mechanical properties. Biomedical Engineering Society Annual Meeting, Philadelphia, PA, October 16-19, 2019. Podium Presentation.

Pancheri NM, Theodossiou SK, Bozeman A, Brumley MR, Schiele NR. Altered neonatal locomotion impacts weight-bearing tendon function, but not collagen morphology. Intermountain Biological Engineering Conference, Logan, UT, November 9, 2019. Poster Presentation.

Pancheri NM, Theodossiou SK, Bozeman A, Brumley MR, Schiele NR. Altered neonatal locomotion impacts weight-bearing tendon function, but not collagen morphology. Idaho INBRE Conference, Moscow, ID, July 29-July 31, 2019. Poster Presentation.

Right: Statewide INBRE 2019 Summer Conference Awards Banquet (top). Neonatal rat Achilles tendon disscetion (bottom). Photos courtesy of Jerome Poulos Photography

Analyzing collagen structure in developing neonatal tendon

Idaho IDeA Network of Biomedical Research Excellence (INBRE) High School to College STEM Transition Trainee¹

In Summer 2018 I was given the opportunity to work in Dr. Nathan Schiele's Tendon Engineering Laboratory in a collaborative research experience between INBRE and the Idaho STEM Action Center. Accordingly, I helped lead a project analyzing how collagen structure develops in neonatal rat tail tendons from postnatal day (P) 1 to P10. Using second harmonic generation (SHG) microscopy to visualize the collagen fivers in tendon, we compared developing collagen structure.

Tendons are collagen-rich musculoskeletal tissues fundamental to locomotion. Unfortunately, tendons are susceptible to injury and have poor healing capacity resulting in long-term functional deficiencies. This motivates the need for engineered replacement tissues. However, tissue engineering strategies are challenged by the limited information on how the collagen structure of tendon develops, particularly on what effect mechanical stimuli has on general tendon development.

The Summer concluded with a poster presentation at the Statewide INBRE 2018 Summer Conference where I placed 1st in the Poster Presentation Competition for the STEM Trainees Category.

Above: "Crimp" collagen structure of P1 neonatal rat tail tendon from Analyzing Collagen Structure in Developing Neonatal Tendons

¹ The project described was supported by an Institutional Development Award (IDeA) from the National Institute of General Medical Sciences of the National Institutes of Health under Grant #P20GM10340

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Research and Projects

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Investigating regulators of tendon formation

2020-2021 Beckman Scholar, Arnold and Mable Beckman Foundation

Potential regulators of LOX production in tenogenically differentiating MSCs