My Internship

Beginning My Internship:

I am an intern at Dr. Melissa Kacena's Lab in the Department of Orthopedic Surgery. I get to experience hands on learning within all areas of the lab setting. I shadow various post doctoral students who each focus on various areas in the lab and different parts of the studies that the lab is working on. I hope to gain a lot of experience and knowledge on how a lab functions as well as refine my lab skills such as pipetting. I am excited to apply what I learn in my courses to hands on training and get a better understanding of how research questions become an experimental process and later turn into published studies. This internship experience will help me become a more well rounded science student in addition to helping me become familiar with a professional setting as I move closer to graduate school and career opportunities.

My Internship Goals:

1. I hope to become a more well-rounded professional student within science by refining my lab skills while learning new interventions and techniques.

• I will be shadowing various lab members as they teach me the different protocols they are working on. A few specific protocols include DNA genotyping, various cell culture assays, and mouse handling.

2. I am hoping to develop a better understanding of how a research lab functions.

• I will complete various perquisite training courses on campus and online which outline how a lab functions and detail different protocols in different situations. In addition, I will be applying the information I learn in these courses as I work hands in Dr. Kacena’s lab.

3. I hope to gain a better comprehension on how to interpret, examine, and explain the purpose and results of research experiments.

• I will have the opportunity to shadow various lab members and follow along all the different techniques and protocols that come with different testing/data collection that all come together as results of the research being studied in Dr. Kacena’s lab.

Halfway Through My Internship:

I have learned a lot so far at my internship. Some lab skills and techniques are things I have learned previously, and now get the chance to improve and refine. A few of these include pipetting, performing PCR, running gel electrophoresis and analyzing the results. Other protocols and skills are completely new to me and pretty exciting be to a part of. A few new things to me are working with mice by feeding and weighing them, and performing various assays such as crystal violet staining and picogreen. What I have come to realize is that it can be challenging to keep up with the big picture of all the different protocols and how they come together to form slowly form the results of the several studies Dr. Kacena's lab is working on. However, I find it helpful to here presentations that other people who work in the lab have put together so the big pictures become clearer.

Internship Duties:

I was later assigned to help on one project that is run by Dr. Diane Wagner and Sonali Karnik. This project focuses on working on tissue engineering strategies. My job for this project was initially to check on mice daily after their surgery. In the following weeks I took x ray images every week of the femur that had undergone surgery.

Project Summary:

With the ever-growing elderly population, age related fractures in the US have been projected to increase from 2.1 million in 2005, to over 3 million in 2025. Unfortunately, the elderly are also at risk for impaired fracture healing as aging causes diminished bone mass and bone quality along with various forms of bone disease. Thus, it is important to develop treatments aimed specifically for this population. While previous studies have tested human mesenchymal stem cells primed towards the more frequently used intramembranous ossification pathway for healing critical size bone defects in immunodeficient animals, this project examines the use of a tissue engineering strategy that primes mesenchymal stem cells, taken from mice, towards the endochondral pathway for bone healing. These cells were then placed into a collagen sponge and implanted into critical sized bone defects in the mouse, and bone healing was tracked via x ray imaging for six weeks. This strategy may provide a greater possibility of cell survival due to the use of cells that resemble hypertrophic chondrocytes, which are well adapted for avascular environments observed at the fracture site.

Background

Aging causes diminished bone mass and bone quality along with various forms of bone disease which can affect the elderly populations incidence of fractures and problems during healing. New interventions are necessary to improve fracture healing, especially for the growing elderly population. Bone formation occurs through two different pathways: intramembranous ossification, such as flat bones of the skull, and endochondral ossification, such as long bones of appendages. Current practices of tissue engineering most commonly utilizes intramembranous ossification. Intramembranous ossification involves mesenchymal stem cells that differentiate to osteoblasts and, after the invasion in capillaries, form mineralized bone. However, intramembranous ossification used for tissue engineering has several drawbacks including low cell viability due to poorly vascularized sites. This project focuses on the less explored pathway of tissue engineering using endochondral ossification. Endochondral ossification begins with hypertrophic chondrocytes that form a cartilaginous template. This cartilaginous template is then remodeled into a vascularized and mineralized tissue. While this pathway has been less studied, there have been successful studies that have healed critical size bone defects in immunodeficient animals using human mesenchymal stem cells. Endochondral ossification as a tissue engineering pathway provides a greater possibility of cell survival with the use of hypertrophic chondrocytes, which are well adapted in avascular environments.

Methods

In this study, mesenchymal stem cells taken from mice are prepared in specific conditions, placed onto collagen sponges in addition to an alginate matrix, and implanted into critical size bone defects in mice where they act as cartilaginous calluses for endochondral ossification to take place.