Kendell Pawelec

Michigan State University | MSU · Department of Radiology

In this paper, we show, for the first time, the key link between scaffold architecture and latent heat evolution during the production of porous biomedical collagen structures using freeze-drying. Collagen scaffolds are used widely in the biomedical industry for the repair and reconstruction of skeletal tissues and organs. Freeze-drying of collagen...

The development of effective treatment options for repair of peripheral nerves is complicated by lack of knowledge concerning the interactions between cells and implants. A promising device, the multichannel scaffold, incorporates microporous channels, aligning glia and directing axonal growth across a nerve gap. To enhance clinical outcomes of ner...

Longitudinal radiological monitoring of biomedical devices is increasingly important, driven by the risk of device failure following implantation. Polymeric devices are poorly visualized with clinical imaging, hampering efforts to use diagnostic imaging to predict failure and enable intervention. Introducing nanoparticle contrast agents into polyme...

Successful tissue engineering requires biomedical devices that initially stabilize wounds, then degrade as tissue is regenerated. However, the material degradation rates reported in literature are often conflicting. Incorporation of in situ monitoring functionality into implanted devices would allow real time assessment of degradation and potential...

3D‐printed biomaterial implants are revolutionizing personalized medicine for tissue repair, especially in orthopedics. In this study, a radiopaque bismuth oxide (Bi2O3) doped polycaprolactone (PCL) composite is developed and implemented to enable the use of diagnostic X‐ray technologies, especially spectral photon counting X‐ray computed tomograph...

Implanted polymeric devices, designed to encourage tissue regeneration, require porosity. However, characterizing porosity, which affects many functional device properties, is non‐trivial. Computed tomography (CT) is a quick, versatile, and non‐destructive way to gain 3D structural information, yet various CT technologies, such as benchtop, preclin...

3D printed biomaterial implants are revolutionizing personalized medicine for tissue repair, especially in orthopedics. In this study, a radiopaque Bi 2 O 3 doped polycaprolactone (PCL) composite is developed and implemented to enable the use of diagnostic X-ray technologies, especially photon counting X-ray computed tomography (PCCT), for comprehe...

Implanted biomedical devices require porosity to encourage tissue regeneration. However, characterizing porosity, which affects many functional device properties, is non-trivial. Computed tomography (CT) is a quick, versatile, and non-destructive way to gain 3D structural information. While optimization of CT for polymeric devices has been investig...

Devices to treat peripheral nerve injury (PNI) must balance many considerations to effectively guide regenerating nerves across a gap and achieve functional recovery. To enhance efficacy, design features like luminal fillers have been explored extensively. Material choice for PNI devices is also critical, as the determining factor of device mechani...

Biomedical implants remain an important clinical tool for restoring patient mobility and quality of life after trauma. While polymers are often used for devices, their degradation profile remains difficult to determine post-implantation. CT monitoring could be a powerful tool for in situ monitoring of devices, but polymers require the introduction...

Repairing peripheral nerve injuries remains a challenge, even with use of auxiliary implantable biomaterial conduits. After implantation the location or function of polymeric devices cannot be assessed via clinical imaging modalities. Adding nanoparticle contrast agents into polymers can introduce radiopacity enabling imaging using computed tomogra...

Longitudinal radiological monitoring of biomedical devices is increasingly important, driven by risk of device failure following implantation. Polymeric devices are poorly visualized with clinical imaging, hampering efforts to use diagnostic imaging to predict failure and enable intervention. Introducing nanoparticle contrast agents into polymers i...

Repairing peripheral nerve injuries remains a clinical challenge. To enhance nerve regeneration and functional recovery, the use of auxiliary implantable biomaterial conduits has become widespread. After implantation, there is currently no way to assess the location or function of polymeric biomedical devices, as they cannot be easily differentiate...

Bleomycin‐induced lung fibrosis is a debilitating disease, linked to high morbidity and mortality in chemotherapy patients. The MRTF/SRF transcription pathway has been proposed as a potential therapeutic target, as it is critical for myofibroblast differentiation, a hallmark of fibrosis. In human lung fibroblasts, the MRTF/SRF pathway inhibitor, CC...

Implantable medical devices from polymeric materials stabilize and repair tissue after trauma or disease. While their use is widespread, it remains difficult to evaluate devices after implantation to ensure proper positioning and determine subsequent device damage, to potentially prevent life-threatening complications. Incorporating radiopacity int...

Drug-induced lung fibrosis is a debilitating disease, linked to high morbidity and mortality. A number of drugs can cause fibrosis, many of which are used to treat cancer, including chemotherapy agents and immune checkpoint inhibitors. The MRTF/SRF transcription pathway has been proposed as a potential therapeutic target, as it is critical for myof...

Clinical effectiveness of implantable medical devices would be improved with in situ monitoring to ensure device positioning, determine subsequent damage, measure biodegradation, and follow healing. While standard clinical imaging protocols are appropriate for diagnosing disease and injury, these protocols have not been vetted for imaging devices....

Within the body, the bone plays many key roles, everything from a support structure, to a protective shell, to a metabolic source of ions. While bone can normally adapt to the changing demands of its environment, when the system breaks down, it can be devastating to the individual and society. The majority of the population will experience an ailme...

In the design and use of implants and therapeutic devices for bone repair, a thorough evaluation of materials properties is vital. These properties, encompassing the mechanics, chemistry, architecture and how the material copes with the physiological environment, dictate the applications for which a material can be used. This chapter discusses mate...

Peripheral nerve injury remains a large clinical problem, with challenges to the successful translation of nerve repair devices. One promising technology is the multichannel scaffold, a conduit incorporating arrays of linear microchannels, which has high open lumen volume to guide regenerating nerves toward distal targets. To maximize open lumen vo...

In a previous study, we demonstrated a novel manufacturing approach to fabricate multi-channel scaffolds (MCS) for use in spinal cord injuries (SCI). In the present study, we extended similar materials processing technology to fabricate significantly longer (5X) porous poly caprolactone (PCL) MCS and evaluated their efficacy in 1 cm sciatic periphe...

Nutrient diffusion and cellular infiltration are important factors for tissue engineering scaffolds. Maximizing both, by optimizing permeability and scaffold architecture, is important to achieve functional recovery. The relationship between scaffold permeability and structure was explored in anisotropic scaffolds from a human collagen I based reco...

Biomineralized scaffolds are an attractive option for bone tissue engineering, being similar to native bone. However, optimization is difficult, due to complex interplay between architecture, chemistry and mechanics. Utilizing biomimetic nucleation, linear mineralized scaffolds were created from a collagen type I based recombinant peptide (RCP). Os...

Recombinant peptides have the power to harness the inherent biocompatibility of natural macro-molecules, while maintaining a defined chemistry for use in tissue engineering. Creating scaffolds from peptides requires stabilization via cross-linking, a process known to alter both mechanics and density of adhesion ligands. The chemistry and mechanics...

The basic building block of the extra-cellular matrix in native tissue is collagen. As a structural protein, collagen has an inherent biocompatibility making it an ideal material for regenerative medicine. Cellular response, mediated by integrins, is dictated by the structure and chemistry of the collagen fibers. Fiber formation, via fibrillogenesi...

Dietary silicon is essential in the maintenance of bone and cartilage. However, the mechanism by which silicon, in the form of silicates, triggers a biological response has never been uncovered. Here we demonstrate the incorporation of orthosilicic acid (Si(OH)4), the form of silicon in the body, within collagen scaffolds for use as an in vitro pla...

The potential applications of ice-templating porous materials are constantly expanding, especially as scaffolds for tissue engineering. Ice-templating, a process utilizing ice nucleation and growth within an aqueous solution, consists of a cooling stage (before ice nucleation) and a freezing stage (during ice formation). While heat release during c...

In recent years, there has been a shift from traditional cell culture on two-dimensional substrates towards the use of three-dimensional scaffolds for tissue engineering. Ice-templating is a versatile tool to create porous scaffolds from collagen. Here we discuss specific considerations for the design of moulds to produce freeze dried collagen scaf...

The structure of ice-templated collagen scaffolds is sensitive to many factors. By adding 0.5 wt% of sodium chloride or sucrose to collagen slurries, scaffold structure could be tuned through changes in ice growth kinetics and interactions of the solute and collagen. With ionic solutes (sodium chloride) the entanglements of the collagen molecule de...

Development of tissue engineering scaffolds relies on careful selection of pore architecture and chemistry of the cellular environment. Repair of skeletal soft tissue, such as tendon, is particularly challenging, since these tissues have a relatively poor healing response. When removed from their native environment, tendon cells (tenocytes) lose th...

Stability of the knee relies on the meniscus, a complex connective tissue with poor healing ability. Current meniscal tissue engineering is inadequate, as the signals for increasing meniscal cell proliferation have not been established. In this study, collagen scaffold structure, isotropic or aligned, and fibrin gel addition were tested. Metabolic...

Ice-templating techniques, including freeze-drying and freeze casting, are extremely versatile and can be used with a variety of materials systems. The process relies on the freezing of a water based solution. During freezing, ice nucleates within the solution and concentrates the solute in the regions between the growing crystals. Once the ice is...

Biopolymer scaffolds have great therapeutic potential within tissue engineering due to their large interconnected porosity and biocompatibility. Using an ice-templated technique, where collagen is concentrated into a porous network by ice nucleation and growth, scaffolds with anisotropic pore architecture can be created, mimicking natural tissues l...

Linearly growing ultrathin polyelectrolyte multilayer (PEM) films of strong polyelectrolytes, poly(diallyldimethylammonium chloride) (PDAC), and sulfonated polystyrene, sodium salt (SPS) exhibit a gradual shift from cytophilic to cytophobic behavior, with increasing thickness for films of less than 100 nm. Previous explanations based on film hydrat...

Axons of the adult central nervous system exhibit an extremely limited ability to regenerate after spinal cord injury. Experimentally generated patterns of axon growth are typically disorganized and randomly oriented. Support of linear axonal growth into spinal cord lesion sites has been demonstrated using arrays of uniaxial channels, templated wit...

Various investigators have proposed that “scientific geniuses” are polymaths. To test this hypothesis, autobiographies, biographies, and obituary notices of Nobel Prize winners in the sciences, members of the Royal Society, and the U.S. National Academy of Sciences were read and adult arts and crafts avocations tabulated. Data were compared with a...