TABLE II.

Proposed methods for implementation of a disease-directed engineering approach. For each section of the perspective, we provide actionable areas of emphasis that a biomedically focused engineering lab could implement to follow a disease-directed engineering approach. We also provide examples of how the actionable areas could be carried out in the lab setting. Where we felt most relevant, we emphasized the critical need for collaborations.

Implementation of a disease-directed engineering approach	Actionable areas of emphasis	Example
Normal physiology should drive experimental design	Include both sexes in all studies	Until the sex dependence of the outcome is established, therapeutic studies should be powered to account for sexual dimorphism
	Use age- and developmentally appropriate models	Evaluate therapeutics for neurodegenerative disease in older animals; or if testing a therapeutic for preterm versus term brain injury, ensure that susceptible brain structures match human development
	Evaluate in multiple species (if available) of the same disease modela	Therapeutic hypothermia for term HIE was shown to be successful in HI models in rats, pigs, and sheep before being translated to the clinic.
Disease physiology should direct treatment intervention	Assess hormonal and gut function via blood hormone levels (LC-MS or ELISAs) and gut permeability (histology), respectively	In experimental TBI, gut function is acutely worse and hormonal function chronically deteriorates, therefore outcomes would need to be statistically adjusted to account for these; or alternatively, therapeutic interventions could be timed for oral delivery when gut permeability is high
	Focus on multiscalar factors for outcome assessmentsb	In MS, look at the molecular and cellular level (immune response), the whole-organ level (imaging, histology), and the whole-organism level (behavior, mortality)
Timing of pathophysiological changes could determine intervention delivery success	Evaluate how delivery of a therapeutic platform is affected by pathological changes at the organ and cellular/extracellular level	Quantify distribution, diffusion, and cellular uptake at different dosing time points after disease onset to account for compensatory pathological changes that might impair (i.e., edema) or improve (i.e., BBB permeability) delivery
	Leverage pathological changes at the appropriate time after disease onset for maximal delivery	AD has chronic BBB impairment in the areas of injury or susceptibility, therefore therapeutics that are long-circulating can be engineered to take advantage of this increased permeability based on the extent and mechanism (i.e., endothelial loss or alteration in transporter expression) of impairment
Reproducibility and translation	Test in multiple models that account for different etiologies that may result in the same phenotypea	Cerebral palsy can result from hypoxia-ischemia, infection, or inflammation, so evaluating a therapeutic in models of these three etiologies that result in motor function loss is essential
	Reproduce experiments in multiple labsa	Partner with collaborators working on the same model in the same species or collaborate with someone who has the same model in a different species
	Include multiple relevant pathologies, when relevant	If performing MCAO to model adult stroke, then include etiological factors such as hypertension, obesity, diabetes

^aCollaboration is key to successfully implementing these measures.

^bFor optimal translation from preclinical to clinical implementation, the multiscalar assessment would need to be performed equally in the preclinical model and in humans.